Papers
1.
García-Inglés, Jorge; Roldán-Piñero, C; Ramos, Diego Alejandro Moreno; Uceda, Rafael G; Cuerva, Juan M; Leary, Edmund; Miguel, Delia; Zotti, Linda A
Conductance oscillations in helicene-based junctions Journal Article
In: Journal of Physics: Condensed Matter, vol. 37, no. 13, pp. 135301, 2025, ISSN: 0953-8984, (Publisher: IOP Publishing).
@article{garcia-ingles_conductance_2025,
title = {Conductance oscillations in helicene-based junctions},
author = {Jorge García-Inglés and C Roldán-Piñero and Diego Alejandro Moreno Ramos and Rafael G Uceda and Juan M Cuerva and Edmund Leary and Delia Miguel and Linda A Zotti},
url = {https://dx.doi.org/10.1088/1361-648X/adaf67},
doi = {10.1088/1361-648X/adaf67},
issn = {0953-8984},
year = {2025},
date = {2025-02-01},
urldate = {2025-03-23},
journal = {Journal of Physics: Condensed Matter},
volume = {37},
number = {13},
pages = {135301},
abstract = {We have carried out a theoretical study into electron transport through molecular junctions based on dithiolated helicenes of varying lengths. We found that, for certain specific structural conditions, in which the orientation and the pitch of the helical structures are kept constant, the transmission at the Fermi level exhibits oscillations as a function of the molecular length, which approximately follow an odd–even pattern. Dispersive interactions alter this trend, however, ensuing a rather different quasi-periodic oscillating pattern with a sawtooth profile.},
note = {Publisher: IOP Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have carried out a theoretical study into electron transport through molecular junctions based on dithiolated helicenes of varying lengths. We found that, for certain specific structural conditions, in which the orientation and the pitch of the helical structures are kept constant, the transmission at the Fermi level exhibits oscillations as a function of the molecular length, which approximately follow an odd–even pattern. Dispersive interactions alter this trend, however, ensuing a rather different quasi-periodic oscillating pattern with a sawtooth profile.
2.
Tabares, Gema; Magro, Raul; Vázquez, Luis; Fernandez, Alejandro; Gordillo, Nuria
MoSe2xTe2–2x alloy for hydrogen gas detection Journal Article
In: Sensors and Actuators A: Physical, vol. 382, pp. 116126, 2025, ISSN: 0924-4247.
@article{tabares_mose2xte22x_2025,
title = {MoSe2xTe2–2x alloy for hydrogen gas detection},
author = {Gema Tabares and Raul Magro and Luis Vázquez and Alejandro Fernandez and Nuria Gordillo},
url = {https://www.sciencedirect.com/science/article/pii/S0924424724011208},
doi = {10.1016/j.sna.2024.116126},
issn = {0924-4247},
year = {2025},
date = {2025-02-01},
urldate = {2025-02-19},
journal = {Sensors and Actuators A: Physical},
volume = {382},
pages = {116126},
abstract = {This study presents one of the first detailed investigation into the out-of-plane growth of two-dimensional MoSe2xTe2–2x for three distinct Se:Te compositions, yielding the samples MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35. Scanning electron microscopy reveals the morphological evolution, showcasing nanoflakes predominantly grown in a random out-of-plane orientation. Raman spectroscopy confirms the crystal structure of MoSe2xTe2–2x samples, with no detectable traces of MoO3 or MoO2 precursors. Distinctive peaks validate the presence of MoSe2xTe2–2x, while spectral shifts suggest at compositional variations. Conductive-Atomic Force Microscopy (C-AFM) was used to quantify current flow between a diamond-doped AFM tip and the sample. Additionally, the resistances of compositions MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35 were characterized, yielding median values of 108.0 Ω, 25.4 kΩ, and 240.0 kΩ, respectively, indicating diverse electrical properties associated with Se content. Notably, the sample with the highest Se content exhibits increased resistivity as anticipated, consistent with XRD spectra results. Finally, gas-sensing performance is evaluated by assessing electrical resistance variations before and after exposure to H2 gas at various temperatures, revealing significant changes indicative of enhanced charge flow upon H2 exposure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study presents one of the first detailed investigation into the out-of-plane growth of two-dimensional MoSe2xTe2–2x for three distinct Se:Te compositions, yielding the samples MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35. Scanning electron microscopy reveals the morphological evolution, showcasing nanoflakes predominantly grown in a random out-of-plane orientation. Raman spectroscopy confirms the crystal structure of MoSe2xTe2–2x samples, with no detectable traces of MoO3 or MoO2 precursors. Distinctive peaks validate the presence of MoSe2xTe2–2x, while spectral shifts suggest at compositional variations. Conductive-Atomic Force Microscopy (C-AFM) was used to quantify current flow between a diamond-doped AFM tip and the sample. Additionally, the resistances of compositions MoSe0.46Te1.55, MoSe0.55Te1.45, and MoSe0.64Te1.35 were characterized, yielding median values of 108.0 Ω, 25.4 kΩ, and 240.0 kΩ, respectively, indicating diverse electrical properties associated with Se content. Notably, the sample with the highest Se content exhibits increased resistivity as anticipated, consistent with XRD spectra results. Finally, gas-sensing performance is evaluated by assessing electrical resistance variations before and after exposure to H2 gas at various temperatures, revealing significant changes indicative of enhanced charge flow upon H2 exposure.
3.
Shuhaib, Jinan H. Al; Ferrer, Isabel J.; Ares, José R.; Cianci, Salvatore; Tuzi, Federico; Blundo, Elena; Polimeni, Antonio; Benayas, Antonio; Marin, Riccardo; Leardini, Fabrice
Sensitized near-infrared lanthanide emission in chalcogenide perovskites Journal Article
In: Journal of Materials Chemistry C, vol. 13, no. 5, pp. 2238–2246, 2025, ISSN: 2050-7534, (Publisher: The Royal Society of Chemistry).
@article{shuhaib_sensitized_2025,
title = {Sensitized near-infrared lanthanide emission in chalcogenide perovskites},
author = {Jinan H. Al Shuhaib and Isabel J. Ferrer and José R. Ares and Salvatore Cianci and Federico Tuzi and Elena Blundo and Antonio Polimeni and Antonio Benayas and Riccardo Marin and Fabrice Leardini},
url = {https://pubs.rsc.org/en/content/articlelanding/2025/tc/d4tc04446k},
doi = {10.1039/D4TC04446K},
issn = {2050-7534},
year = {2025},
date = {2025-01-01},
urldate = {2025-03-09},
journal = {Journal of Materials Chemistry C},
volume = {13},
number = {5},
pages = {2238–2246},
abstract = {Semiconductor materials capable of hosting luminescent lanthanide ions (Ln3+) and sensitize their emission are scarce. Halide perovskites are prime systems for this purpose, yet they often feature toxic elements (e.g., lead) in their composition and have reduced stability. The discovery of alternative semiconductors that feature host-to-Ln3+ energy transfer mechanisms – while being more stable and environmentally benign – would thus broaden the applicability of this class of luminescent materials. Herein, we report near-infrared (NIR) emitting phosphors made of BaZrS3 chalcogenide perovskite doped with Ln3+ ions (Ln = Yb, Er, Nd). We chose BaZrS3 because it features (i) crystallographic sites that can accommodate Ln3+ ions, (ii) high light absorption coefficient in the visible, and (iii) stability. The phosphors were prepared via sulfurization of Ln3+-doped BaZrO3 microparticles obtained by a microwave-assisted procedure. The so-obtained Ln3+-doped BaZrS3 display low-temperature NIR emission characteristic of each Ln3+ ion when exciting the matrix. Following photoluminescence studies on doped and undoped BaZrS3 as a function of temperature, we propose an energy level scheme that explains the rich NIR photoluminescence displayed by these phosphors. The obtained results pave the way for the optimization of Ln3+-doped BaZrS3 for optical applications and are expected to spur the study of other ternary chalcogenides sensitization of Ln3+ luminescence.},
note = {Publisher: The Royal Society of Chemistry},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Semiconductor materials capable of hosting luminescent lanthanide ions (Ln3+) and sensitize their emission are scarce. Halide perovskites are prime systems for this purpose, yet they often feature toxic elements (e.g., lead) in their composition and have reduced stability. The discovery of alternative semiconductors that feature host-to-Ln3+ energy transfer mechanisms – while being more stable and environmentally benign – would thus broaden the applicability of this class of luminescent materials. Herein, we report near-infrared (NIR) emitting phosphors made of BaZrS3 chalcogenide perovskite doped with Ln3+ ions (Ln = Yb, Er, Nd). We chose BaZrS3 because it features (i) crystallographic sites that can accommodate Ln3+ ions, (ii) high light absorption coefficient in the visible, and (iii) stability. The phosphors were prepared via sulfurization of Ln3+-doped BaZrO3 microparticles obtained by a microwave-assisted procedure. The so-obtained Ln3+-doped BaZrS3 display low-temperature NIR emission characteristic of each Ln3+ ion when exciting the matrix. Following photoluminescence studies on doped and undoped BaZrS3 as a function of temperature, we propose an energy level scheme that explains the rich NIR photoluminescence displayed by these phosphors. The obtained results pave the way for the optimization of Ln3+-doped BaZrS3 for optical applications and are expected to spur the study of other ternary chalcogenides sensitization of Ln3+ luminescence.
4.
Sanz-García, Juan Antonio; Lifante-Pedrola, Ginés; Santiuste, Juan Enrique Muñoz; Cantelar, Eugenio
Dual luminescent nano-thermometry based on the selective excitation of optical centers in CaF2:Er3+ nanoparticles Journal Article
In: Journal of Alloys and Compounds, vol. 1010, pp. 177529, 2025, ISSN: 0925-8388.
@article{sanz-garcia_dual_2025,
title = {Dual luminescent nano-thermometry based on the selective excitation of optical centers in CaF2:Er3+ nanoparticles},
author = {Juan Antonio Sanz-García and Ginés Lifante-Pedrola and Juan Enrique Muñoz Santiuste and Eugenio Cantelar},
url = {https://www.sciencedirect.com/science/article/pii/S0925838824041173},
doi = {10.1016/j.jallcom.2024.177529},
issn = {0925-8388},
year = {2025},
date = {2025-01-01},
urldate = {2025-02-19},
journal = {Journal of Alloys and Compounds},
volume = {1010},
pages = {177529},
abstract = {We present a study about the feasibility of using the upconverted luminescence of CaF2:Er3+ nanoparticles (NPs), under near infrared excitation within the 4I15/2 → 4I11/2 absorption band, for thermal detection. In order to perform this study, it has been needed to investigate the upconversion processes as function of the Er3+ concentration and the excitation wavelength by using a tunable Ti:Sapphire laser. The results obtained indicate that, under this excitation scheme, the green (2H11/2:4S3/2) and red (4F9/2) emitting levels are populated through different multiphoton processes: Excited state absorption and energy transfer upconversion. Therefore, the ratio between the green and red emissions is also dependent on the Er3+ concentration and the excitation wavelength. Measurements based on site-selective emission/excitation, performed at room temperature, indicate that in these NPs there are at least two different optical centers whose emission bands can be isolated by an appropriate selection of the excitation wavelength. One these centers is compatible with the presence of isolated Er3+ ions, while the other one is tentatively related to the presence of clusters or aggregates. The upconverted luminescence of each optical center is analyzed as function of temperature by means of the ratiometric Fluorescence Intensity Ratio technique. The results indicate that both optical centers exhibit adequate thermal performances and relative sensitivities to be used in thermal sensing.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a study about the feasibility of using the upconverted luminescence of CaF2:Er3+ nanoparticles (NPs), under near infrared excitation within the 4I15/2 → 4I11/2 absorption band, for thermal detection. In order to perform this study, it has been needed to investigate the upconversion processes as function of the Er3+ concentration and the excitation wavelength by using a tunable Ti:Sapphire laser. The results obtained indicate that, under this excitation scheme, the green (2H11/2:4S3/2) and red (4F9/2) emitting levels are populated through different multiphoton processes: Excited state absorption and energy transfer upconversion. Therefore, the ratio between the green and red emissions is also dependent on the Er3+ concentration and the excitation wavelength. Measurements based on site-selective emission/excitation, performed at room temperature, indicate that in these NPs there are at least two different optical centers whose emission bands can be isolated by an appropriate selection of the excitation wavelength. One these centers is compatible with the presence of isolated Er3+ ions, while the other one is tentatively related to the presence of clusters or aggregates. The upconverted luminescence of each optical center is analyzed as function of temperature by means of the ratiometric Fluorescence Intensity Ratio technique. The results indicate that both optical centers exhibit adequate thermal performances and relative sensitivities to be used in thermal sensing.
5.
Rached, A.; Wederni, M. A.; Alaya, S.; Martín-Palma, R. J.; Khirouni, K.
Effects of the substitution in the two sites on barium titanate properties Journal Article
In: Inorganic Chemistry Communications, vol. 172, 2025.
@article{rached_effects_2025,
title = {Effects of the substitution in the two sites on barium titanate properties},
author = {A. Rached and M. A. Wederni and S. Alaya and R. J. Martín-Palma and K. Khirouni},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211161739&doi=10.1016%2fj.inoche.2024.113675&partnerID=40&md5=d4ccd1056fece039e03f7b658bf18d89},
doi = {10.1016/j.inoche.2024.113675},
year = {2025},
date = {2025-01-01},
journal = {Inorganic Chemistry Communications},
volume = {172},
abstract = {Barium titanate compound has been studied given their many interesting physico-chemical properties, including their dielectric and ferroelectric behavior. Besides, the introduction of different elements in the barium titanate matrix increases the number of applications in which these compounds can be used. Within this context, in the present work we investigated the effect of doping barium titanate with alkali ions (Ca) and rare earth ions (Er) in Ba sites and by tin ions in Ti sites. The synthesized compound, termed BETS-Ca, was prepared via a solid–solid reaction technique. X-ray diffraction measurements indicated that the material has a tetragonal symmetry structure. Scanning electron microscopy analysis allowed to identify a dense microstructure with the existence of both grain and grain boundaries. Moreover, optical absorbance and infrared spectra indicated the incorporation of doping elements such as erbium and tin. Additionally, the electric and dielectric properties of the compounds were investigated. AC conductivity analysis suggested that conduction is governed by correlated barriers hopping and non overlapping small polaron tunneling processes. Nyquist plot showed the contribution of both grain and grain boundaries to the conduction. Finally, a ferroelectric-paraelectric transition was found around a specific temperature (TC = 360 K). According to the Curie-Weiss law, this transition has a diffusive character. © 2024 Elsevier B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Barium titanate compound has been studied given their many interesting physico-chemical properties, including their dielectric and ferroelectric behavior. Besides, the introduction of different elements in the barium titanate matrix increases the number of applications in which these compounds can be used. Within this context, in the present work we investigated the effect of doping barium titanate with alkali ions (Ca) and rare earth ions (Er) in Ba sites and by tin ions in Ti sites. The synthesized compound, termed BETS-Ca, was prepared via a solid–solid reaction technique. X-ray diffraction measurements indicated that the material has a tetragonal symmetry structure. Scanning electron microscopy analysis allowed to identify a dense microstructure with the existence of both grain and grain boundaries. Moreover, optical absorbance and infrared spectra indicated the incorporation of doping elements such as erbium and tin. Additionally, the electric and dielectric properties of the compounds were investigated. AC conductivity analysis suggested that conduction is governed by correlated barriers hopping and non overlapping small polaron tunneling processes. Nyquist plot showed the contribution of both grain and grain boundaries to the conduction. Finally, a ferroelectric-paraelectric transition was found around a specific temperature (TC = 360 K). According to the Curie-Weiss law, this transition has a diffusive character. © 2024 Elsevier B.V.
6.
Saddik, K. Ben; Hernández, M. J.; Pampillón, M. A.; Cervera, M.; García, B. J.
On the absorption coefficient of GaP1-xNx layers and its potential application for silicon photovoltaics Journal Article
In: Materials Science in Semiconductor Processing, vol. 185, 2025.
@article{ben_saddik_absorption_2025,
title = {On the absorption coefficient of GaP1-xNx layers and its potential application for silicon photovoltaics},
author = {K. Ben Saddik and M. J. Hernández and M. A. Pampillón and M. Cervera and B. J. García},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85206315773&doi=10.1016%2fj.mssp.2024.109011&partnerID=40&md5=3aa2b52744ca9b9eb92377cf4971b44f},
doi = {10.1016/j.mssp.2024.109011},
year = {2025},
date = {2025-01-01},
journal = {Materials Science in Semiconductor Processing},
volume = {185},
abstract = {The absorption coefficient and the energy gap of GaP1-xNx layers has been obtained by spectroscopic ellipsometry for samples grown on Si(001) substrates by chemical beam epitaxy with N mole fractions in the range 0 ≤ x ≤ 0.081. The resulting absorption spectra exhibit a direct band-like behavior near the absorption edge. The absorption coefficient values increase with the N content, reaching values in the range α ∼ 1-2x104 cm−1 in the vicinity of the absorption edge below the original GaP direct bandgap, which are comparable to those obtained for high efficiency solar cell materials. Furthermore, dependence of the absorption coefficient with increasing N content points to a strong GaP Γ-like character of the conduction-band wave function of GaP1-xNx alloys near the Brillouin zone center at k = 0, as predicted by the band anticrossing model. Bandgap energy values obtained by spectroscopic ellipsometry are compared with previous values obtained by photoluminescence measurements on the same samples, observing a shift of about 50–100 meV. Finally, the value of the band anticrossing parameter coupling the N level and the host GaP conduction band has been obtained from the dependence of both, the bandgap and the absorption coefficient, with the N content (2.1 and 3.3 eV respectively). © 2024},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The absorption coefficient and the energy gap of GaP1-xNx layers has been obtained by spectroscopic ellipsometry for samples grown on Si(001) substrates by chemical beam epitaxy with N mole fractions in the range 0 ≤ x ≤ 0.081. The resulting absorption spectra exhibit a direct band-like behavior near the absorption edge. The absorption coefficient values increase with the N content, reaching values in the range α ∼ 1-2x104 cm−1 in the vicinity of the absorption edge below the original GaP direct bandgap, which are comparable to those obtained for high efficiency solar cell materials. Furthermore, dependence of the absorption coefficient with increasing N content points to a strong GaP Γ-like character of the conduction-band wave function of GaP1-xNx alloys near the Brillouin zone center at k = 0, as predicted by the band anticrossing model. Bandgap energy values obtained by spectroscopic ellipsometry are compared with previous values obtained by photoluminescence measurements on the same samples, observing a shift of about 50–100 meV. Finally, the value of the band anticrossing parameter coupling the N level and the host GaP conduction band has been obtained from the dependence of both, the bandgap and the absorption coefficient, with the N content (2.1 and 3.3 eV respectively). © 2024
7.
Caukwell, J.; Assenza, S.; Hassan, K. A.; Neilan, B. A.; Clulow, A. J.; Manni, L. Salvati; Fong, W. -K.
Lipidic drug delivery systems are responsive to the human microbiome Journal Article
In: Journal of Colloid and Interface Science, vol. 677, pp. 293–302, 2025.
@article{caukwell_lipidic_2025,
title = {Lipidic drug delivery systems are responsive to the human microbiome},
author = {J. Caukwell and S. Assenza and K. A. Hassan and B. A. Neilan and A. J. Clulow and L. Salvati Manni and W. -K. Fong},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85201165361&doi=10.1016%2fj.jcis.2024.07.216&partnerID=40&md5=a0a246b5664c78e364c50092b07da390},
doi = {10.1016/j.jcis.2024.07.216},
year = {2025},
date = {2025-01-01},
journal = {Journal of Colloid and Interface Science},
volume = {677},
pages = {293–302},
abstract = {In vitro and in vivo tests for therapeutic agents are typically conducted in sterile environments, but many target areas for drug delivery are home to thousands of microbial species. Here, we examine the behaviour of lipidic nanomaterials after exposure to representative strains of four bacterial species found in the gastrointestinal tract and skin. Small angle X-ray scattering measurements show that the nanostructure of monoolein cubic and inverse hexagonal phases are transformed, respectively, into inverse hexagonal and inverse micellar cubic phases upon exposure to a strain of live Staphylococcus aureus often present on skin and mucosa. Further investigation demonstrates that enzymatic hydrolysis and cell membrane lipid transfer are both likely responsible for this effect. The structural responses to S. aureus are rapid and significantly reduce the rate of drug release from monoolein-based nanomaterials. These findings are the first to demonstrate how a key species in the live human microbiome can trigger changes in the structure and drug release properties of lipidic nanomaterials. The effect appears to be strain specific, varies from patient to patient and body region to body region, and is anticipated to affect the bioapplication of monoglyceride-based formulations. © 2024 The Author(s)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In vitro and in vivo tests for therapeutic agents are typically conducted in sterile environments, but many target areas for drug delivery are home to thousands of microbial species. Here, we examine the behaviour of lipidic nanomaterials after exposure to representative strains of four bacterial species found in the gastrointestinal tract and skin. Small angle X-ray scattering measurements show that the nanostructure of monoolein cubic and inverse hexagonal phases are transformed, respectively, into inverse hexagonal and inverse micellar cubic phases upon exposure to a strain of live Staphylococcus aureus often present on skin and mucosa. Further investigation demonstrates that enzymatic hydrolysis and cell membrane lipid transfer are both likely responsible for this effect. The structural responses to S. aureus are rapid and significantly reduce the rate of drug release from monoolein-based nanomaterials. These findings are the first to demonstrate how a key species in the live human microbiome can trigger changes in the structure and drug release properties of lipidic nanomaterials. The effect appears to be strain specific, varies from patient to patient and body region to body region, and is anticipated to affect the bioapplication of monoglyceride-based formulations. © 2024 The Author(s)
8.
Toural, J. L. Sánchez; García-Pérez, J.; Bernardo-Gavito, R.; Granados, D.; Andrino-Gómez, A.; García, G.; Pau, J. L.; Ramos, M. A.; Gordillo, N.
Diamond-defect engineering of NV− centers using ion beam irradiation Journal Article
In: Diamond and Related Materials, vol. 151, 2025.
@article{sanchez_toural_diamond-defect_2025,
title = {Diamond-defect engineering of NV− centers using ion beam irradiation},
author = {J. L. Sánchez Toural and J. García-Pérez and R. Bernardo-Gavito and D. Granados and A. Andrino-Gómez and G. García and J. L. Pau and M. A. Ramos and N. Gordillo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85210653060&doi=10.1016%2fj.diamond.2024.111838&partnerID=40&md5=f60b4304bf40959bc9d51444326d396f},
doi = {10.1016/j.diamond.2024.111838},
year = {2025},
date = {2025-01-01},
journal = {Diamond and Related Materials},
volume = {151},
abstract = {The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV−) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV− centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV− and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800 °C (and in some cases at 900 °C), most samples exhibited a high density of NV0 and especially NV− centers. This demonstrates that thermal treatment is essential for vacancy‑nitrogen recombination and NV− formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV− densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV− center formation to enhance the sensitivity of diamond-based quantum magnetic sensors. © 2024 The Authors},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV−) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV− centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV− and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800 °C (and in some cases at 900 °C), most samples exhibited a high density of NV0 and especially NV− centers. This demonstrates that thermal treatment is essential for vacancy‑nitrogen recombination and NV− formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV− densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV− center formation to enhance the sensitivity of diamond-based quantum magnetic sensors. © 2024 The Authors
9.
Rodríguez-Tapiador, M. I.; Mánuel, J. M.; Blanco, E.; Márquez, E.; Gordillo, N.; Sainz, R.; Merino, J.; Fernández, S.
In: Materials Science in Semiconductor Processing, vol. 188, 2025.
@article{rodriguez-tapiador_effect_2025,
title = {Effect of N2 concentration on structural, morphological, and optoelectronic properties of Cu3N films fabricated by RF magnetron sputtering for photodetection applications},
author = {M. I. Rodríguez-Tapiador and J. M. Mánuel and E. Blanco and E. Márquez and N. Gordillo and R. Sainz and J. Merino and S. Fernández},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211193003&doi=10.1016%2fj.mssp.2024.109176&partnerID=40&md5=29230c71895b36332c9e6b9fca52f871},
doi = {10.1016/j.mssp.2024.109176},
year = {2025},
date = {2025-01-01},
journal = {Materials Science in Semiconductor Processing},
volume = {188},
abstract = {Copper nitride (Cu3N) is a promising eco-friendly material for photodetection and photovoltaic absorption. This study focuses on fabricating high-quality Cu3N thin films via reactive radio-frequency magnetron sputtering, using pure N2 and N2/Ar mixture environments, respectively. We investigate how variations in the substrate temperature and the working gas pressure affect absorption capabilities. Phase structure analysis confirms an anti-ReO3 structure with a preferred (100) orientation, and lattice parameters between 0.3810 and 0.3832 nm, with electrical resistivity around 104 Ω cm, indicating a semiconductor character. The films exhibit improved crystalline quality when deposited in pure N2 at 100 °C. Rutherford Backscattering Spectrometry reveals non-stoichiometric films with Cu/N ratios close to 3. The work function showed by the films deposited in N2/Ar is approximately 4.45 eV, while for those deposited in pure N2, the values range from 4.30 to 4.62 eV. Optical properties show a high absorbance and a variable refractive index depending on the deposition conditions. Lastly, the Cu3N films deposited at 100 °C in pure N2 exhibit enhanced photocurrent and photosensitivity of 3.78 × 10−8 A and 9644.9 %, respectively, at 10 V and using AM1.5G as light source. This result underscores the importance of plasma composition as a key factor for obtaining a material with great potential to be applied in such applications. © 2024},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Copper nitride (Cu3N) is a promising eco-friendly material for photodetection and photovoltaic absorption. This study focuses on fabricating high-quality Cu3N thin films via reactive radio-frequency magnetron sputtering, using pure N2 and N2/Ar mixture environments, respectively. We investigate how variations in the substrate temperature and the working gas pressure affect absorption capabilities. Phase structure analysis confirms an anti-ReO3 structure with a preferred (100) orientation, and lattice parameters between 0.3810 and 0.3832 nm, with electrical resistivity around 104 Ω cm, indicating a semiconductor character. The films exhibit improved crystalline quality when deposited in pure N2 at 100 °C. Rutherford Backscattering Spectrometry reveals non-stoichiometric films with Cu/N ratios close to 3. The work function showed by the films deposited in N2/Ar is approximately 4.45 eV, while for those deposited in pure N2, the values range from 4.30 to 4.62 eV. Optical properties show a high absorbance and a variable refractive index depending on the deposition conditions. Lastly, the Cu3N films deposited at 100 °C in pure N2 exhibit enhanced photocurrent and photosensitivity of 3.78 × 10−8 A and 9644.9 %, respectively, at 10 V and using AM1.5G as light source. This result underscores the importance of plasma composition as a key factor for obtaining a material with great potential to be applied in such applications. © 2024
10.
Jiménez-Vivanco, María R.; Lugo, Eduardo; Torres-Costa, Vicente; Martín-Palma, Raúl J.; Santana, Maricela; Herrera, Raúl
Determination of the complex refractive index of free-standing porous silicon and oxidized porous silicon in the Visible and Ultraviolet range Journal Article
In: Applied Physics A, vol. 130, no. 12, pp. 952, 2024, ISSN: 1432-0630.
@article{jimenez-vivanco_determination_2024,
title = {Determination of the complex refractive index of free-standing porous silicon and oxidized porous silicon in the Visible and Ultraviolet range},
author = {María R. Jiménez-Vivanco and Eduardo Lugo and Vicente Torres-Costa and Raúl J. Martín-Palma and Maricela Santana and Raúl Herrera},
url = {https://doi.org/10.1007/s00339-024-08129-8},
doi = {10.1007/s00339-024-08129-8},
issn = {1432-0630},
year = {2024},
date = {2024-12-01},
urldate = {2024-12-01},
journal = {Applied Physics A},
volume = {130},
number = {12},
pages = {952},
abstract = {This work determined the spectral values in the 250–850 wavelength regions of the complex refractive index, n and k, for free-standing porous silicon (PS) and oxidized PS layers. These values were extracted from the experimental reflectance and transmittance spectra. One of the free-standing PS layers was fabricated with high porosity, and the other had low porosity. Thereafter, both layers were oxidized by dry oxidation to achieve a free-standing oxidized PS layer. The oxidation of the porous structures dramatically affects the optical properties of the free-standing layers, especially in the short wavelength Ultraviolet and Visible ranges, since the average transmittance enormously increases, reaching almost 90% at some specific points. Also, we found that the average value of the refractive index and extinction coefficient is higher for PS layers with lower porosity than those with higher porosity. The extinction coefficient and refractive index values are further reduced by oxidizing the free-standing PS layers in the 250–850 wavelength region. The reader can see a zero extinction coefficient value for the oxidized PS layer manufactured with high porosity. Our results show that due to a dry oxidation process in an air environment, the absorption coefficient can be reduced until reaching a value of zero. Due to that, it could be possible to design photonic crystals such as Microcavities, Fibonacci structures, waveguides, and Rugate filters without optical losses caused by light absorption in the Ultraviolet and Visible regions. Pore diameter, thickness and Energy-dispersive X-ray spectroscopy (EDS) elemental spectrum of two different PS layers were determined.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This work determined the spectral values in the 250–850 wavelength regions of the complex refractive index, n and k, for free-standing porous silicon (PS) and oxidized PS layers. These values were extracted from the experimental reflectance and transmittance spectra. One of the free-standing PS layers was fabricated with high porosity, and the other had low porosity. Thereafter, both layers were oxidized by dry oxidation to achieve a free-standing oxidized PS layer. The oxidation of the porous structures dramatically affects the optical properties of the free-standing layers, especially in the short wavelength Ultraviolet and Visible ranges, since the average transmittance enormously increases, reaching almost 90% at some specific points. Also, we found that the average value of the refractive index and extinction coefficient is higher for PS layers with lower porosity than those with higher porosity. The extinction coefficient and refractive index values are further reduced by oxidizing the free-standing PS layers in the 250–850 wavelength region. The reader can see a zero extinction coefficient value for the oxidized PS layer manufactured with high porosity. Our results show that due to a dry oxidation process in an air environment, the absorption coefficient can be reduced until reaching a value of zero. Due to that, it could be possible to design photonic crystals such as Microcavities, Fibonacci structures, waveguides, and Rugate filters without optical losses caused by light absorption in the Ultraviolet and Visible regions. Pore diameter, thickness and Energy-dispersive X-ray spectroscopy (EDS) elemental spectrum of two different PS layers were determined.
11.
Taleb, Amjad Al; Viñes, Francesc; Farías, Daniel
Suppression of Elastic Scattering of CH4 by Graphene Passivation of Ni(111) Journal Article
In: The Journal of Physical Chemistry C, vol. 128, no. 49, pp. 21182–21189, 2024, ISSN: 1932-7447, (Publisher: American Chemical Society).
@article{al_taleb_suppression_2024,
title = {Suppression of Elastic Scattering of CH4 by Graphene Passivation of Ni(111)},
author = {Amjad Al Taleb and Francesc Viñes and Daniel Farías},
url = {https://doi.org/10.1021/acs.jpcc.4c06132},
doi = {10.1021/acs.jpcc.4c06132},
issn = {1932-7447},
year = {2024},
date = {2024-12-01},
urldate = {2025-03-09},
journal = {The Journal of Physical Chemistry C},
volume = {128},
number = {49},
pages = {21182–21189},
abstract = {We report high-resolution angular diffraction measurements of CH4 and Ne from Ni(111) and from a graphene (Gr) layer grown on Ni(111), whose effective atomic mass is enhanced by the strong Gr–Ni interaction. The incident energies are between 43 and 68 meV for Ne, and between 62 and 108 meV for CH4 beams. Sharp diffraction features are observed with Ne beams from both Ni(111) and Gr/Ni(111) surfaces. However, using methane beams, clear diffraction peaks are observed only from Ni(111), with broad angular distributions measured from Gr/Ni(111), as expected for classical particles, with no quantum features. This is surprising, since Ne and methane have similar masses and therefore a comparable quantum behavior is expected for the same incident energy. This effect is mainly due to the larger physisorption well of CH4 on Gr/Ni(111), as shown by DFT calculations, in addition to the larger corrugation of the potential energy surface and the excitation of phonon modes of the graphene overlayer.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report high-resolution angular diffraction measurements of CH4 and Ne from Ni(111) and from a graphene (Gr) layer grown on Ni(111), whose effective atomic mass is enhanced by the strong Gr–Ni interaction. The incident energies are between 43 and 68 meV for Ne, and between 62 and 108 meV for CH4 beams. Sharp diffraction features are observed with Ne beams from both Ni(111) and Gr/Ni(111) surfaces. However, using methane beams, clear diffraction peaks are observed only from Ni(111), with broad angular distributions measured from Gr/Ni(111), as expected for classical particles, with no quantum features. This is surprising, since Ne and methane have similar masses and therefore a comparable quantum behavior is expected for the same incident energy. This effect is mainly due to the larger physisorption well of CH4 on Gr/Ni(111), as shown by DFT calculations, in addition to the larger corrugation of the potential energy surface and the excitation of phonon modes of the graphene overlayer.
12.
Ramírez, R.; Tarazona, P.; Chacón, E.; Herrero, C. P.
Strain-dependent elastic constants of solid membranes Journal Article
In: Physical Review B, vol. 110, no. 23, pp. 235417, 2024, (Publisher: American Physical Society).
@article{ramirez_strain-dependent_2024,
title = {Strain-dependent elastic constants of solid membranes},
author = {R. Ramírez and P. Tarazona and E. Chacón and C. P. Herrero},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.235417},
doi = {10.1103/PhysRevB.110.235417},
year = {2024},
date = {2024-12-01},
urldate = {2025-03-09},
journal = {Physical Review B},
volume = {110},
number = {23},
pages = {235417},
abstract = {Computer simulations were conducted to explore the equilibrium states of a planar crystalline membrane as a function of external strain and temperature. The employed models include the continuous elastic Nelson-Peliti Hamiltonian, which describes the anharmonic coupling between in-plane and out-of-plane membrane fluctuations, and the atomistic long-range carbon bond-order potential (LCBOPII), which is designed to describe carbon interactions. The primary focus of the simulations is on studying the elastic constants of graphene: the compressibility modulus 𝐵 and the Lamé coefficient 𝜇. By analyzing the stability conditions in terms of the elastic constants, we can determine the region of thermodynamic stability for the planar morphology of the membrane as a function of external strain and temperature. The instability is associated with the vanishing of one of the elastic coefficients. Depending on the elastic response of the system, thermodynamic instability may be caused either by the condition 𝐵=0 or 𝜇=0. The symmetry of the intrinsic anharmonicity of the model determines its elastic response to decreasing tensile stress. The two studied models provide different predictions for the membrane properties near the critical point. The continuous Nelson-Peliti model predicts auxetic behavior, with a Poisson's ratio of 𝜈=−1 at the critical point. In contrast, the atomistic LCBOPII model exhibits a positive Poisson's ratio, which becomes 𝜈=1 at the critical point. Our findings challenge the generally accepted view that a Poisson's ratio of 𝜈=−1/3 is a universal property of unstrained crystalline membranes. Instead, our results highlight that anharmonic effects may cause significant differences in the mechanical responses, especially near the critical point of instability.},
note = {Publisher: American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Computer simulations were conducted to explore the equilibrium states of a planar crystalline membrane as a function of external strain and temperature. The employed models include the continuous elastic Nelson-Peliti Hamiltonian, which describes the anharmonic coupling between in-plane and out-of-plane membrane fluctuations, and the atomistic long-range carbon bond-order potential (LCBOPII), which is designed to describe carbon interactions. The primary focus of the simulations is on studying the elastic constants of graphene: the compressibility modulus 𝐵 and the Lamé coefficient 𝜇. By analyzing the stability conditions in terms of the elastic constants, we can determine the region of thermodynamic stability for the planar morphology of the membrane as a function of external strain and temperature. The instability is associated with the vanishing of one of the elastic coefficients. Depending on the elastic response of the system, thermodynamic instability may be caused either by the condition 𝐵=0 or 𝜇=0. The symmetry of the intrinsic anharmonicity of the model determines its elastic response to decreasing tensile stress. The two studied models provide different predictions for the membrane properties near the critical point. The continuous Nelson-Peliti model predicts auxetic behavior, with a Poisson's ratio of 𝜈=−1 at the critical point. In contrast, the atomistic LCBOPII model exhibits a positive Poisson's ratio, which becomes 𝜈=1 at the critical point. Our findings challenge the generally accepted view that a Poisson's ratio of 𝜈=−1/3 is a universal property of unstrained crystalline membranes. Instead, our results highlight that anharmonic effects may cause significant differences in the mechanical responses, especially near the critical point of instability.
13.
Hernández, R. Magro; Muñoz-Noval, A.; Briz, J. A.; Murias, J. R.; Espinosa-Rodríguez, A.; Fraile, L. M.; Agulló-Rueda, F.; Ynsa, M. D.; de Sousa, C. Tavares; Cortés-Llanos, B.; López, G. García; Nácher, E.; García-Tavora, V.; i Geli, N. Mont; Nerio, A.; Onecha, V. V.; Pallàs, M.; Tarifeño, A.; Tengblad, O.; Silván, M. Manso; Viñals, S.
Iodine-substituted hydroxyapatite nanoparticles and activation of derived ceramics for range verification in proton therapy Journal Article
In: Journal of Materials Chemistry B, vol. 12, no. 46, pp. 12030–12037, 2024, ISSN: 2050-7518, (Publisher: The Royal Society of Chemistry).
@article{hernandez_iodine-substituted_2024,
title = {Iodine-substituted hydroxyapatite nanoparticles and activation of derived ceramics for range verification in proton therapy},
author = {R. Magro Hernández and A. Muñoz-Noval and J. A. Briz and J. R. Murias and A. Espinosa-Rodríguez and L. M. Fraile and F. Agulló-Rueda and M. D. Ynsa and C. Tavares de Sousa and B. Cortés-Llanos and G. García López and E. Nácher and V. García-Tavora and N. Mont i Geli and A. Nerio and V. V. Onecha and M. Pallàs and A. Tarifeño and O. Tengblad and M. Manso Silván and S. Viñals},
url = {https://pubs.rsc.org/en/content/articlelanding/2024/tb/d4tb01391c},
doi = {10.1039/D4TB01391C},
issn = {2050-7518},
year = {2024},
date = {2024-11-01},
urldate = {2025-03-09},
journal = {Journal of Materials Chemistry B},
volume = {12},
number = {46},
pages = {12030–12037},
abstract = {Osteosarcoma is a radioresistant cancer, and proton therapy is a promising radiation alternative for treating cancer with the advantage of a high dose concentration in the tumor area. In this work, we propose the use of iodine-substituted hydroxyapatite (IHAP) nanomaterials to use iodine (127I) as a proton radiation tracer, providing access to range verification studies in mineralized tissues. For this purpose, the nanomaterials were synthesized at four iodine concentrations via hydrothermal synthesis. The materials were characterized via different microstructural techniques to identify an optimal high iodine concentration and pure apatite phase nanomaterial. Finally, such pure IHAP powders were shaped and irradiated with proton beams of 6 and 10 MeV, and their activation was demonstrated through subsequent decay analysis. The materials could be integrated into phantom structures for the verification of doses and ranges of protons prior to animal testing and clinical proton therapy treatments of tumors located deep under combined soft and calcified tissues.},
note = {Publisher: The Royal Society of Chemistry},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Osteosarcoma is a radioresistant cancer, and proton therapy is a promising radiation alternative for treating cancer with the advantage of a high dose concentration in the tumor area. In this work, we propose the use of iodine-substituted hydroxyapatite (IHAP) nanomaterials to use iodine (127I) as a proton radiation tracer, providing access to range verification studies in mineralized tissues. For this purpose, the nanomaterials were synthesized at four iodine concentrations via hydrothermal synthesis. The materials were characterized via different microstructural techniques to identify an optimal high iodine concentration and pure apatite phase nanomaterial. Finally, such pure IHAP powders were shaped and irradiated with proton beams of 6 and 10 MeV, and their activation was demonstrated through subsequent decay analysis. The materials could be integrated into phantom structures for the verification of doses and ranges of protons prior to animal testing and clinical proton therapy treatments of tumors located deep under combined soft and calcified tissues.
14.
Margetis, Dionisios; Gómez-Santos, Guillermo; Stauber, Tobias
Optical response of alternating twisted trilayer graphene Journal Article
In: Physical Review B, vol. 110, no. 20, pp. 205144, 2024, (Publisher: American Physical Society).
@article{margetis_optical_2024,
title = {Optical response of alternating twisted trilayer graphene},
author = {Dionisios Margetis and Guillermo Gómez-Santos and Tobias Stauber},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.205144},
doi = {10.1103/PhysRevB.110.205144},
year = {2024},
date = {2024-11-01},
urldate = {2025-03-09},
journal = {Physical Review B},
volume = {110},
number = {20},
pages = {205144},
abstract = {We study the optical response of the alternating twisted trilayer graphene by making use of a unitary transformation for the trilayer Hamiltonian and the Kubo formulation of linear response theory. The layer-resolved optical conductivities are expressed in terms of contributions from effective twisted bilayer and single-layer systems along with their coupling. We show that the in-plane magnetic response is proportional to this coupling between the twisted bilayer and single-layer systems; and, due to the different energy scales, the in-plane magnetic response is negligibly small. We also formulate a local electromagnetic response that involves the vertical gradients of the magnetic field and moment.},
note = {Publisher: American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We study the optical response of the alternating twisted trilayer graphene by making use of a unitary transformation for the trilayer Hamiltonian and the Kubo formulation of linear response theory. The layer-resolved optical conductivities are expressed in terms of contributions from effective twisted bilayer and single-layer systems along with their coupling. We show that the in-plane magnetic response is proportional to this coupling between the twisted bilayer and single-layer systems; and, due to the different energy scales, the in-plane magnetic response is negligibly small. We also formulate a local electromagnetic response that involves the vertical gradients of the magnetic field and moment.
15.
Szewczyk, Daria; Moratalla, Manuel; Chajewski, Grzegorz; Gebbia, Jonathan F.; Jeżowski, Andrzej; Krivchikov, Alexander I.; Barrio, María; Tamarit, Josep Ll.; Ramos, M. A.
Specific heat at low temperatures in quasiplanar molecular crystals: Origin of glassy anomalies in minimally disordered crystals Journal Article
In: Physical Review B, vol. 110, no. 17, pp. 174204, 2024, (Publisher: American Physical Society).
@article{szewczyk_specific_2024,
title = {Specific heat at low temperatures in quasiplanar molecular crystals: Origin of glassy anomalies in minimally disordered crystals},
author = {Daria Szewczyk and Manuel Moratalla and Grzegorz Chajewski and Jonathan F. Gebbia and Andrzej Jeżowski and Alexander I. Krivchikov and María Barrio and Josep Ll. Tamarit and M. A. Ramos},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.174204},
doi = {10.1103/PhysRevB.110.174204},
year = {2024},
date = {2024-11-01},
urldate = {2025-02-21},
journal = {Physical Review B},
volume = {110},
number = {17},
pages = {174204},
abstract = {We present low-temperature specific heat (𝐶p) measurements of a monoclinic 𝑃21/𝑐 crystal formed by quasiplanar molecules of tetrachloro-𝑚-xylene. The dynamic disorder frozen at low temperature of the asymmetric unit (formed by a half molecule) consists of reorientation around a threefold-like axis perpendicular to the benzene ring. Such a minimal disorder gives rise to typical glassy anomalies, as a linear contribution in 𝐶p ascribed to two-level systems and a broad maximum around 6.6 K in 𝐶p/𝑇3 (the boson peak). We discuss these results in the framework of other quasiplanar molecular crystals with different accountable numbers of in-plane molecular orientations. We find that the density of two-level systems does not correlate with the degree of orientational disorder. Rather, it is the molecular asymmetry that seems to play a relevant role in the thermal anomalies. Furthermore, we discuss the suggested correlation between the boson peak (𝑇BP) and Debye (Θ𝐷) temperatures. We find that a linear correlation between 𝑇BP and Θ𝐷 holds for many—but not all—structural glasses and strikingly holds even better for some disordered crystals, including our studied quasiplanar molecular crystals.},
note = {Publisher: American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present low-temperature specific heat (𝐶p) measurements of a monoclinic 𝑃21/𝑐 crystal formed by quasiplanar molecules of tetrachloro-𝑚-xylene. The dynamic disorder frozen at low temperature of the asymmetric unit (formed by a half molecule) consists of reorientation around a threefold-like axis perpendicular to the benzene ring. Such a minimal disorder gives rise to typical glassy anomalies, as a linear contribution in 𝐶p ascribed to two-level systems and a broad maximum around 6.6 K in 𝐶p/𝑇3 (the boson peak). We discuss these results in the framework of other quasiplanar molecular crystals with different accountable numbers of in-plane molecular orientations. We find that the density of two-level systems does not correlate with the degree of orientational disorder. Rather, it is the molecular asymmetry that seems to play a relevant role in the thermal anomalies. Furthermore, we discuss the suggested correlation between the boson peak (𝑇BP) and Debye (Θ𝐷) temperatures. We find that a linear correlation between 𝑇BP and Θ𝐷 holds for many—but not all—structural glasses and strikingly holds even better for some disordered crystals, including our studied quasiplanar molecular crystals.
16.
González, Juan Pedro Ramírez; Cinacchi, Giorgio
Non-nematicity of the filamentary phase in systems of hard minor circular arcs Journal Article
In: Physical Review E, vol. 110, no. 4, pp. 044701, 2024, (Publisher: American Physical Society).
@article{gonzalez_non-nematicity_2024,
title = {Non-nematicity of the filamentary phase in systems of hard minor circular arcs},
author = {Juan Pedro Ramírez González and Giorgio Cinacchi},
url = {https://link.aps.org/doi/10.1103/PhysRevE.110.044701},
doi = {10.1103/PhysRevE.110.044701},
year = {2024},
date = {2024-10-01},
urldate = {2025-03-09},
journal = {Physical Review E},
volume = {110},
number = {4},
pages = {044701},
abstract = {This work further investigates an aspect of the phase behavior of hard circular arcs whose phase diagram has been recently calculated by Monte Carlo numerical simulations: the non-nematicity of the filamentary phase that hard minor circular arcs form. Both second-virial density-functional theory and further Monte Carlo numerical simulations find that the positional one-particle density function undulates in the direction transverse to the axes of the filaments while further Monte Carlo numerical simulations find that the mobility of the hard minor circular arcs across the filaments occurs via a mechanism reminiscent of the mechanism of diffusion in a smectic phase: the filamentary phase is not a “modulated” [“splay(-bend)”] nematic phase.},
note = {Publisher: American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This work further investigates an aspect of the phase behavior of hard circular arcs whose phase diagram has been recently calculated by Monte Carlo numerical simulations: the non-nematicity of the filamentary phase that hard minor circular arcs form. Both second-virial density-functional theory and further Monte Carlo numerical simulations find that the positional one-particle density function undulates in the direction transverse to the axes of the filaments while further Monte Carlo numerical simulations find that the mobility of the hard minor circular arcs across the filaments occurs via a mechanism reminiscent of the mechanism of diffusion in a smectic phase: the filamentary phase is not a “modulated” [“splay(-bend)”] nematic phase.
17.
Ramadan, Rehab; Martín-Palma, Raúl J.
Enhancing piezoresistive sensitivity of PEDOT:PSS-based strain sensors through nickel microparticles incorporation Journal Article
In: Journal of Materials Science, vol. 59, no. 40, pp. 19138–19151, 2024, ISSN: 1573-4803.
@article{ramadan_enhancing_2024,
title = {Enhancing piezoresistive sensitivity of PEDOT:PSS-based strain sensors through nickel microparticles incorporation},
author = {Rehab Ramadan and Raúl J. Martín-Palma},
url = {https://doi.org/10.1007/s10853-024-10244-z},
doi = {10.1007/s10853-024-10244-z},
issn = {1573-4803},
year = {2024},
date = {2024-10-01},
urldate = {2025-03-09},
journal = {Journal of Materials Science},
volume = {59},
number = {40},
pages = {19138–19151},
abstract = {The following work explores the creation and advancement of a highly sensitive piezoresistive strain sensor. This sensor is composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with a layer of interconnected Ni microparticles (NiMPs) on its surface. The interconnection of NiMPs was achieved through a new simple and cost-effective method using a magnetic bar. Additionally, the elasticity of the PEDOT:PSS membrane is enhanced by incorporating polyvinyl alcohol (PVA). The piezoresistive strain sensor, consisting of PEDOT:PSS, PVA, and NiMPs, was examined to assess its electrical signal, stability, and response time under various strains and bending angles, ranging from 0 to 28%. This range covers typical human body movements. The results demonstrated that the pristine PEDOT:PSS membrane has no piezoresistive effect, while the modified one with NiMPs, it shows a gauge factor value of 174 at high strain levels. Additionally, the sensor’s performance was tested with human finger motions, revealing a significant response to changes in finger movement. The modified method of evenly distributing metallic particles can be used with various magnetic particles such as iron, cobalt, steel, or manganese.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The following work explores the creation and advancement of a highly sensitive piezoresistive strain sensor. This sensor is composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with a layer of interconnected Ni microparticles (NiMPs) on its surface. The interconnection of NiMPs was achieved through a new simple and cost-effective method using a magnetic bar. Additionally, the elasticity of the PEDOT:PSS membrane is enhanced by incorporating polyvinyl alcohol (PVA). The piezoresistive strain sensor, consisting of PEDOT:PSS, PVA, and NiMPs, was examined to assess its electrical signal, stability, and response time under various strains and bending angles, ranging from 0 to 28%. This range covers typical human body movements. The results demonstrated that the pristine PEDOT:PSS membrane has no piezoresistive effect, while the modified one with NiMPs, it shows a gauge factor value of 174 at high strain levels. Additionally, the sensor’s performance was tested with human finger motions, revealing a significant response to changes in finger movement. The modified method of evenly distributing metallic particles can be used with various magnetic particles such as iron, cobalt, steel, or manganese.
18.
Balduque, José; Mecha, Adrián; Sánchez, Rafael
Thermal junctions controlled with Aharonov–Bohm phases Journal Article
In: APL Quantum, vol. 1, no. 3, pp. 036120, 2024, ISSN: 2835-0103.
@article{balduque_thermal_2024,
title = {Thermal junctions controlled with Aharonov–Bohm phases},
author = {José Balduque and Adrián Mecha and Rafael Sánchez},
url = {https://doi.org/10.1063/5.0218032},
doi = {10.1063/5.0218032},
issn = {2835-0103},
year = {2024},
date = {2024-09-01},
urldate = {2025-03-23},
journal = {APL Quantum},
volume = {1},
number = {3},
pages = {036120},
abstract = {Unlike charge, heat flows are difficult to control. We show that, in mesoscopic conductors, electronic thermal currents can be manipulated with a magnetic field by using the Aharonov–Bohm effect: the magnetic control of the interference pattern enhances the thermoelectric effect, while heat transport can be totally suppressed. In a three-terminal configuration, the flux-induced broken reciprocity generates a nonlocal thermoelectric response and translates to the circulation of heat. This way, efficient thermoelectric generators, thermal switches, thermal circulators, and energy harvesters can be defined for minimally disturbing thermal management at the nanoscale.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Unlike charge, heat flows are difficult to control. We show that, in mesoscopic conductors, electronic thermal currents can be manipulated with a magnetic field by using the Aharonov–Bohm effect: the magnetic control of the interference pattern enhances the thermoelectric effect, while heat transport can be totally suppressed. In a three-terminal configuration, the flux-induced broken reciprocity generates a nonlocal thermoelectric response and translates to the circulation of heat. This way, efficient thermoelectric generators, thermal switches, thermal circulators, and energy harvesters can be defined for minimally disturbing thermal management at the nanoscale.
19.
Ayani, Cosme G.; Bosnar, Mihovil; Calleja, Fabian; Solé, Andrés Pinar; Stetsovych, Oleksandr; Ibarburu, Iván M.; Rebanal, Clara; Garnica, Manuela; Miranda, Rodolfo; Otrokov, Mikhail M.; Ondráček, Martin; Jelínek, Pavel; Arnau, Andrés; de Parga, Amadeo L. Vázquez
Unveiling the Interlayer Interaction in a 1H/1T TaS2 van der Waals Heterostructure Journal Article
In: Nano Letters, vol. 24, no. 35, pp. 10805–10812, 2024, ISSN: 1530-6984, (Publisher: American Chemical Society).
@article{ayani_unveiling_2024,
title = {Unveiling the Interlayer Interaction in a 1H/1T TaS2 van der Waals Heterostructure},
author = {Cosme G. Ayani and Mihovil Bosnar and Fabian Calleja and Andrés Pinar Solé and Oleksandr Stetsovych and Iván M. Ibarburu and Clara Rebanal and Manuela Garnica and Rodolfo Miranda and Mikhail M. Otrokov and Martin Ondráček and Pavel Jelínek and Andrés Arnau and Amadeo L. Vázquez de Parga},
url = {https://doi.org/10.1021/acs.nanolett.4c02068},
doi = {10.1021/acs.nanolett.4c02068},
issn = {1530-6984},
year = {2024},
date = {2024-09-01},
urldate = {2025-03-09},
journal = {Nano Letters},
volume = {24},
number = {35},
pages = {10805–10812},
abstract = {This study delves into the intriguing properties of the 1H/1T-TaS2 van der Waals heterostructure, focusing on the transparency of the 1H layer to the charge density wave of the underlying 1T layer. Despite the sizable interlayer separation and metallic nature of the 1H layer, positive bias voltages result in a pronounced superposition of the 1T charge density wave structure on the 1H layer. The conventional explanation relying on tunneling effects proves insufficient. Through a comprehensive investigation combining low-temperature scanning tunneling microscopy, scanning tunneling spectroscopy, non-contact atomic force microscopy, and first-principles calculations, we propose an alternative interpretation. The transparency effect arises from a weak yet substantial electronic coupling between the 1H and 1T layers, challenging prior understanding of the system. Our results highlight the critical role played by interlayer electronic interactions in van der Waals heterostructures to determine the final ground states of the systems.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study delves into the intriguing properties of the 1H/1T-TaS2 van der Waals heterostructure, focusing on the transparency of the 1H layer to the charge density wave of the underlying 1T layer. Despite the sizable interlayer separation and metallic nature of the 1H layer, positive bias voltages result in a pronounced superposition of the 1T charge density wave structure on the 1H layer. The conventional explanation relying on tunneling effects proves insufficient. Through a comprehensive investigation combining low-temperature scanning tunneling microscopy, scanning tunneling spectroscopy, non-contact atomic force microscopy, and first-principles calculations, we propose an alternative interpretation. The transparency effect arises from a weak yet substantial electronic coupling between the 1H and 1T layers, challenging prior understanding of the system. Our results highlight the critical role played by interlayer electronic interactions in van der Waals heterostructures to determine the final ground states of the systems.
20.
Tuero, Pablo; González-Ruano, César; Lu, Yuan; Tiusan, Coriolan; Aliev, Farkhad G.
Spin texture and spin-orbit coupling contributions in spin-triplet superconductivity Journal Article
In: Physical Review B, vol. 110, no. 9, pp. 094504, 2024, (Publisher: American Physical Society).
@article{tuero_spin_2024,
title = {Spin texture and spin-orbit coupling contributions in spin-triplet superconductivity},
author = {Pablo Tuero and César González-Ruano and Yuan Lu and Coriolan Tiusan and Farkhad G. Aliev},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.094504},
doi = {10.1103/PhysRevB.110.094504},
year = {2024},
date = {2024-09-01},
urldate = {2025-02-21},
journal = {Physical Review B},
volume = {110},
number = {9},
pages = {094504},
abstract = {Over the past decade, it has been proposed theoretically and confirmed experimentally that long-range spin-triplet (LRT) superconductivity can be generated in superconductor/ferromagnet hybrids either by the presence of spin textures (ST-LRT) or owing to spin-orbit coupling (SOC-LRT). Nevertheless, there has been no theoretical or experimental investigation to date suggesting that both contributions could simultaneously exist within an experimental system. To disentangle these contributions, we present a comprehensive study of superconducting quasiparticle interference effects taking place inside a ferromagnetic layer interfacing a superconductor, through the investigation of above-gap conductance anomalies (CAs) related to MacMillan-Rowell resonances. The bias dependence of the CAs has been studied under a wide range of in-plane (IP) and out-of-plane (OOP) magnetic fields in two types of epitaxial, V/MgO/Fe-based ferromagnet-superconductor junctions with interfacial spin-orbit coupling. We observe an anisotropy of the CA amplitude under small IP and OOP magnetic fields while remaining weakly affected by high fields, and implement micromagnetic simulations to help us distinguish between the ST-LRT and SOC-LRT contributions. Our findings suggest that further exploration of Fabry-Pérot-type interference effects in electron transport could yield valuable insights into the hybridization between superconductors and ferromagnets induced by spin-orbit coupling and spin textures.},
note = {Publisher: American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Over the past decade, it has been proposed theoretically and confirmed experimentally that long-range spin-triplet (LRT) superconductivity can be generated in superconductor/ferromagnet hybrids either by the presence of spin textures (ST-LRT) or owing to spin-orbit coupling (SOC-LRT). Nevertheless, there has been no theoretical or experimental investigation to date suggesting that both contributions could simultaneously exist within an experimental system. To disentangle these contributions, we present a comprehensive study of superconducting quasiparticle interference effects taking place inside a ferromagnetic layer interfacing a superconductor, through the investigation of above-gap conductance anomalies (CAs) related to MacMillan-Rowell resonances. The bias dependence of the CAs has been studied under a wide range of in-plane (IP) and out-of-plane (OOP) magnetic fields in two types of epitaxial, V/MgO/Fe-based ferromagnet-superconductor junctions with interfacial spin-orbit coupling. We observe an anisotropy of the CA amplitude under small IP and OOP magnetic fields while remaining weakly affected by high fields, and implement micromagnetic simulations to help us distinguish between the ST-LRT and SOC-LRT contributions. Our findings suggest that further exploration of Fabry-Pérot-type interference effects in electron transport could yield valuable insights into the hybridization between superconductors and ferromagnets induced by spin-orbit coupling and spin textures.