Papers
1861.
Segovia, P.; Castro, G.; Mascaraque, A.; Prieto, P.; Kim, H.; Michel, E.
Origin of the surface metallization in single-domain K/Si(100)2×1 Journal Article
In: Physical Review B - Condensed Matter and Materials Physics, vol. 54, no. 20, pp. R14277–R14280, 1996.
@article{segovia_origin_1996,
title = {Origin of the surface metallization in single-domain K/Si(100)2×1},
author = {P. Segovia and G. Castro and A. Mascaraque and P. Prieto and H. Kim and E. Michel},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0343371178&doi=10.1103%2fPhysRevB.54.R14277&partnerID=40&md5=6d5045e325b30b7dc83cadc0452da424},
doi = {10.1103/PhysRevB.54.R14277},
year = {1996},
date = {1996-01-01},
journal = {Physical Review B - Condensed Matter and Materials Physics},
volume = {54},
number = {20},
pages = {R14277–R14280},
abstract = {The electronic structure and the metallization onset of single-domain K/Si(100)2×1 have been investigated with angle-resolved polarization-sensitive ultraviolet photoemission. The electronic states producing the surface metallization have been studied for increasing K coverages up to room-temperature saturation. As K coverage increases, the interface undergoes a transition at a critical coverage, from a low-coverage semiconducting phase, to a saturation-coverage metallic phase. Two different surface states ((Formula presented) and (Formula presented)) have been detected in the vicinity of the Fermi level. These two states are sequentially filled along the metallization process. The coverage dependence of both (Formula presented) and (Formula presented), and their symmetry properties indicate that the metallization is due to the filling of an initially empty surface band (appearance of (Formula presented)). We relate (Formula presented) to the completion of K chains in the single-domain surface. The changes detected in K 3p line shape correlate well with the modifications of the valence band, and support that the surface remains semiconducting up to the filling of (Formula presented). © 1996 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The electronic structure and the metallization onset of single-domain K/Si(100)2×1 have been investigated with angle-resolved polarization-sensitive ultraviolet photoemission. The electronic states producing the surface metallization have been studied for increasing K coverages up to room-temperature saturation. As K coverage increases, the interface undergoes a transition at a critical coverage, from a low-coverage semiconducting phase, to a saturation-coverage metallic phase. Two different surface states ((Formula presented) and (Formula presented)) have been detected in the vicinity of the Fermi level. These two states are sequentially filled along the metallization process. The coverage dependence of both (Formula presented) and (Formula presented), and their symmetry properties indicate that the metallization is due to the filling of an initially empty surface band (appearance of (Formula presented)). We relate (Formula presented) to the completion of K chains in the single-domain surface. The changes detected in K 3p line shape correlate well with the modifications of the valence band, and support that the surface remains semiconducting up to the filling of (Formula presented). © 1996 The American Physical Society.
1862.
Zapata, I.; Bartussek, R.; Sols, F.; Hänggi, P.
Voltage rectification by a squid ratchet Journal Article
In: Physical Review Letters, vol. 77, no. 11, pp. 2292–2295, 1996.
@article{zapata_voltage_1996,
title = {Voltage rectification by a squid ratchet},
author = {I. Zapata and R. Bartussek and F. Sols and P. Hänggi},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001576101&doi=10.1103%2fPhysRevLett.77.2292&partnerID=40&md5=4bf448f481a9b79a439e1fc54f5e7a66},
doi = {10.1103/PhysRevLett.77.2292},
year = {1996},
date = {1996-01-01},
journal = {Physical Review Letters},
volume = {77},
number = {11},
pages = {2292–2295},
abstract = {We argue that the phase across an asymmetric dc SQUID threaded by a magnetic flux can experience an effective ratchet (periodic and asymmetric) potential. Under an external ac current, a rocking ratchet mechanism operates whereby one sign of the time derivative of the phase is favored. We show that there exists a range of parameters in which a fixed sign (and, in a narrower range, even a fixed value) of the average voltage across the ring occurs, regardless of the sign of the external current dc component. © 1996 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We argue that the phase across an asymmetric dc SQUID threaded by a magnetic flux can experience an effective ratchet (periodic and asymmetric) potential. Under an external ac current, a rocking ratchet mechanism operates whereby one sign of the time derivative of the phase is favored. We show that there exists a range of parameters in which a fixed sign (and, in a narrower range, even a fixed value) of the average voltage across the ring occurs, regardless of the sign of the external current dc component. © 1996 The American Physical Society.
1863.
Heras, C. De Las; Vidales, J. L. Martín De; Ferrer, I. J.; Sánchez, C.
Structural and microstructural features of pyrite FeS2-x thin films obtained by thermal sulfuration of iron Journal Article
In: Journal of Materials Research, vol. 11, no. 1, pp. 211–220, 1996.
@article{de_las_heras_structural_1996,
title = {Structural and microstructural features of pyrite FeS2-x thin films obtained by thermal sulfuration of iron},
author = {C. De Las Heras and J. L. Martín De Vidales and I. J. Ferrer and C. Sánchez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029775541&doi=10.1557%2fJMR.1996.0026&partnerID=40&md5=85cbc054d0d60f9660ec51c33551c4ea},
doi = {10.1557/JMR.1996.0026},
year = {1996},
date = {1996-01-01},
journal = {Journal of Materials Research},
volume = {11},
number = {1},
pages = {211–220},
abstract = {Structural and microstructural properties of synthetic thin films of pyrite (FeS2-x), prepared by thermal sulfuration of iron layers, were investigated from Rietveld refinements of x-ray diffraction data, collected by step/scan mode. From this refinement lattice constant, a, and sulfur position parameter, u nearest neighbor Fe-S and S-S bond distances and letrahedral and octahedral bond angles have been determined. Moreover, sulfur deficit in the samples, surface and volume-weighted crystallite size and microstrains were also obtained. From these data, the influence of of temperature and time of sulfuration and sulfur pressure on their structural and microstructural propeties has been established. Stoichiometric pyrite thin films are obtained by sulfurating the iron films at low temperatures (Ts∼ 600-700 K) during short times (ts ∼ 0.5-2 h). These experimental conditions yield films with the highest a, u, Fe-S bond distance, and microstrains, as well as S/Fe ratios about 2.00, i.e., null sulfur vacancies, the smallest S-S bond distances, and crystallite size. Finally, the possible influence of these structural and microstructural characteristics on some physical properties (optical absorption, electrical resistivity ⋯) of the films is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Structural and microstructural properties of synthetic thin films of pyrite (FeS2-x), prepared by thermal sulfuration of iron layers, were investigated from Rietveld refinements of x-ray diffraction data, collected by step/scan mode. From this refinement lattice constant, a, and sulfur position parameter, u nearest neighbor Fe-S and S-S bond distances and letrahedral and octahedral bond angles have been determined. Moreover, sulfur deficit in the samples, surface and volume-weighted crystallite size and microstrains were also obtained. From these data, the influence of of temperature and time of sulfuration and sulfur pressure on their structural and microstructural propeties has been established. Stoichiometric pyrite thin films are obtained by sulfurating the iron films at low temperatures (Ts∼ 600-700 K) during short times (ts ∼ 0.5-2 h). These experimental conditions yield films with the highest a, u, Fe-S bond distance, and microstrains, as well as S/Fe ratios about 2.00, i.e., null sulfur vacancies, the smallest S-S bond distances, and crystallite size. Finally, the possible influence of these structural and microstructural characteristics on some physical properties (optical absorption, electrical resistivity ⋯) of the films is discussed.
1864.
Viña, L.; Calleja, J.; Cros, A.; Cantarero, A.
Role of excitons in double Raman resonances in GaAs quantum wells Journal Article
In: Physical Review B - Condensed Matter and Materials Physics, vol. 53, no. 7, pp. 3975–3982, 1996.
@article{vina_role_1996,
title = {Role of excitons in double Raman resonances in GaAs quantum wells},
author = {L. Viña and J. Calleja and A. Cros and A. Cantarero},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0642310309&doi=10.1103%2fPhysRevB.53.3975&partnerID=40&md5=c03460919b76069e440e0a2ad7030390},
doi = {10.1103/PhysRevB.53.3975},
year = {1996},
date = {1996-01-01},
journal = {Physical Review B - Condensed Matter and Materials Physics},
volume = {53},
number = {7},
pages = {3975–3982},
abstract = {Raman scattering by longitudinal-optical phonons has been measured in GaAs-AlAs multiple quantum wells at high magnetic fields. Doubly resonant scattering processes are observed at photon energies corresponding to magneto-excitons with different principal quantum numbers for the incoming and outgoing channels. The existence of these initially forbidden scattering processes, their resonance energies, and their relative intensities are correctly reproduced by our theoretical description. The model takes into account the excitonic nature of the intermediate states, as well as scattering processes involving a nonzero in-plane phonon wave vector, which is required to allow inter-Landau level scattering of the exciton. © 1996 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Raman scattering by longitudinal-optical phonons has been measured in GaAs-AlAs multiple quantum wells at high magnetic fields. Doubly resonant scattering processes are observed at photon energies corresponding to magneto-excitons with different principal quantum numbers for the incoming and outgoing channels. The existence of these initially forbidden scattering processes, their resonance energies, and their relative intensities are correctly reproduced by our theoretical description. The model takes into account the excitonic nature of the intermediate states, as well as scattering processes involving a nonzero in-plane phonon wave vector, which is required to allow inter-Landau level scattering of the exciton. © 1996 The American Physical Society.
1865.
Aliev, F. G.; Vieira, S.; Villar, R.; Martinez, J. L.; Seaman, C. L.; Maple, M. B.
Anomalous ground state in U0.9Th0.1Be13 Journal Article
In: Physica B: Physics of Condensed Matter, vol. 206-207, no. C, pp. 454–456, 1995.
@article{aliev_anomalous_1995,
title = {Anomalous ground state in U0.9Th0.1Be13},
author = {F. G. Aliev and S. Vieira and R. Villar and J. L. Martinez and C. L. Seaman and M. B. Maple},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029247458&doi=10.1016%2f0921-4526%2894%2900488-H&partnerID=40&md5=6020c72742332ae62fe460f070effc3b},
doi = {10.1016/0921-4526(94)00488-H},
year = {1995},
date = {1995-01-01},
journal = {Physica B: Physics of Condensed Matter},
volume = {206-207},
number = {C},
pages = {454–456},
abstract = {By studying the transformation of transport, calorimetric and magnetic properties of UxTh1-xBe13 (0.64 ≤ x ≤ 1) solid solutions, we have found that U0.9Th0.1Be13 displays a non-Fermi liquid ground state which corresponds to the two channel Kondo effect (TCKE). For the first time, together with the anomalous temperature dependences of the thermodynamic properties, we have observed that the resistivity changes as the square root of temperature, as had been predicted theoretically for TCKE. © 1995.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
By studying the transformation of transport, calorimetric and magnetic properties of UxTh1-xBe13 (0.64 ≤ x ≤ 1) solid solutions, we have found that U0.9Th0.1Be13 displays a non-Fermi liquid ground state which corresponds to the two channel Kondo effect (TCKE). For the first time, together with the anomalous temperature dependences of the thermodynamic properties, we have observed that the resistivity changes as the square root of temperature, as had been predicted theoretically for TCKE. © 1995.
1866.
Sanchez-Portal, D.; Artacho, E.; Soler, J. M.
Projection of plane-wave calculations into atomic orbitals Journal Article
In: Solid State Communications, vol. 95, no. 10, pp. 685–690, 1995.
@article{sanchez-portal_projection_1995,
title = {Projection of plane-wave calculations into atomic orbitals},
author = {D. Sanchez-Portal and E. Artacho and J. M. Soler},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029378786&doi=10.1016%2f0038-1098%2895%2900341-X&partnerID=40&md5=b07daf7527310fba9c9e2d11cb3ce307},
doi = {10.1016/0038-1098(95)00341-X},
year = {1995},
date = {1995-01-01},
journal = {Solid State Communications},
volume = {95},
number = {10},
pages = {685–690},
abstract = {The projection of the eigenfunctions obtained in standard plane-wave first-principle electronic-structure calculations into atomic-orbital basis sets is proposed as a formal and practical link between the methods based on plane waves and the ones based on atomic orbitals. Given a candidate atomic basis, (i) its quality is evaluated by its projection into the plane-wave eigenfunctions, (ii) it is optimized by maximizing that projection, (iii) the associated tight-binding hamiltonian and energy bands are obtained, and (iv) population analysis is performed in a natural way. The proposed method replaces the traditional trial-and-error procedures of finding appropriate atomic bases and the fitting of bands to obtain tight-binding hamiltonians. Test calculations of some zincblende semiconductors are presented. © 1995.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The projection of the eigenfunctions obtained in standard plane-wave first-principle electronic-structure calculations into atomic-orbital basis sets is proposed as a formal and practical link between the methods based on plane waves and the ones based on atomic orbitals. Given a candidate atomic basis, (i) its quality is evaluated by its projection into the plane-wave eigenfunctions, (ii) it is optimized by maximizing that projection, (iii) the associated tight-binding hamiltonian and energy bands are obtained, and (iv) population analysis is performed in a natural way. The proposed method replaces the traditional trial-and-error procedures of finding appropriate atomic bases and the fitting of bands to obtain tight-binding hamiltonians. Test calculations of some zincblende semiconductors are presented. © 1995.
1867.
Plentz, F.; Meneses, E. A.; Meseguer, F.; Sánchez-Dehesa, J.
New AlxGa1-xAs related deep luminescence observed in modulation doped quantum wells Journal Article
In: Journal of Applied Physics, vol. 77, no. 11, pp. 5946–5949, 1995.
@article{plentz_new_1995,
title = {New AlxGa1-xAs related deep luminescence observed in modulation doped quantum wells},
author = {F. Plentz and E. A. Meneses and F. Meseguer and J. Sánchez-Dehesa},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36449003659&doi=10.1063%2f1.359176&partnerID=40&md5=3bf8eb6c178be18f447a3accb228ba49},
doi = {10.1063/1.359176},
year = {1995},
date = {1995-01-01},
journal = {Journal of Applied Physics},
volume = {77},
number = {11},
pages = {5946–5949},
abstract = {An emission band that appears in the high energy side of the photoluminescence spectra of a modulation doped multiple quantum well structure was investigated by means of magneto-photoluminescence and photoluminescence excitation spectroscopy. We show that this emission band is related to the Al0.36Ga0.64As layers of the structure. We analyze the data within the framework of the configuration coordinate model and attribute this photoluminescence band to the recombination of electrons trapped to a new deep center in the alloy and the photogenerated holes. © 1995 American Institute of Physics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An emission band that appears in the high energy side of the photoluminescence spectra of a modulation doped multiple quantum well structure was investigated by means of magneto-photoluminescence and photoluminescence excitation spectroscopy. We show that this emission band is related to the Al0.36Ga0.64As layers of the structure. We analyze the data within the framework of the configuration coordinate model and attribute this photoluminescence band to the recombination of electrons trapped to a new deep center in the alloy and the photogenerated holes. © 1995 American Institute of Physics.
1868.
Prieto, P.; Fernández, A.; Soriano, L.; Yubero, F.; Elizalde, E.; González-Elipe, A. R.; Sanz, J. M.
Electronic structure of insulating Zr3N4 studied by resonant photoemission Journal Article
In: Physical Review B, vol. 51, no. 24, pp. 17984–17987, 1995.
@article{prieto_electronic_1995,
title = {Electronic structure of insulating Zr3N4 studied by resonant photoemission},
author = {P. Prieto and A. Fernández and L. Soriano and F. Yubero and E. Elizalde and A. R. González-Elipe and J. M. Sanz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000346678&doi=10.1103%2fPhysRevB.51.17984&partnerID=40&md5=9d41411c88f749b68f434db169e624fa},
doi = {10.1103/PhysRevB.51.17984},
year = {1995},
date = {1995-01-01},
journal = {Physical Review B},
volume = {51},
number = {24},
pages = {17984–17987},
abstract = {The formation of insulating Zr3N4 by low-energy (5 KeV) N2+ bombardment of zirconium was studied by photoemission spectroscopy using synchrotron radiation. The electronic structure of Zr3N4 was then studied by resonant photoemission in the 32-80-eV photon-energy range. Resonance effects have been observed at ∼41 and at ∼50 eV, well above the Zr 4p binding energy (∼29.5 eV) as measured by photoemission. The resonance at 41 eV is shown to be associated with the enhancement of those valence-band states with an important Zr 4d character. In fact, it has been used to isolate the cationic Zr 4d contribution to the valence band of Zr3N4. Furthermore, we have identified those regions of the valence band with a predominant N 2p character by direct photoemission at hν70 eV for which the Zr 4d photoemission cross section is negligible. A broad resonance at hν=50 eV seems to be caused by resonant processes involving N 2p states, however, the exact mechanism implicated remains unknown. © 1995 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The formation of insulating Zr3N4 by low-energy (5 KeV) N2+ bombardment of zirconium was studied by photoemission spectroscopy using synchrotron radiation. The electronic structure of Zr3N4 was then studied by resonant photoemission in the 32-80-eV photon-energy range. Resonance effects have been observed at ∼41 and at ∼50 eV, well above the Zr 4p binding energy (∼29.5 eV) as measured by photoemission. The resonance at 41 eV is shown to be associated with the enhancement of those valence-band states with an important Zr 4d character. In fact, it has been used to isolate the cationic Zr 4d contribution to the valence band of Zr3N4. Furthermore, we have identified those regions of the valence band with a predominant N 2p character by direct photoemission at hν70 eV for which the Zr 4d photoemission cross section is negligible. A broad resonance at hν=50 eV seems to be caused by resonant processes involving N 2p states, however, the exact mechanism implicated remains unknown. © 1995 The American Physical Society.
1869.
Eteläniemi, V.
Br/Si(211)2×1 structure investigated by x-ray standing wave Proceedings Article
In: pp. 1583–1588, 1995, (Issue: 3).
@inproceedings{etelaniemi_brsi21121_1995,
title = {Br/Si(211)2×1 structure investigated by x-ray standing wave},
author = {V. Eteläniemi},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-21844526061&doi=10.1116%2f1.579732&partnerID=40&md5=060756f8a8687d5f3ad9e547f13c828d},
doi = {10.1116/1.579732},
year = {1995},
date = {1995-01-01},
volume = {13},
number = {3},
pages = {1583–1588},
abstract = {The Br/Si(211)2×1 interface was investigated using the x-ray standing wave technique. Three different Bragg reflections [(111), (220) and (422)] were used to determine the adsorption sites following a triangulation method. In all the interfaces prepared, Br adsorption reverted the 2×1 substrate reconstruction to 1×1. Br atoms occupy different sites depending on the preparation conditions: The conventional atop site of the [111]-like terraces of the surface, and also along the unsaturated dangling bonds of the [100]-like steps present at the surface. A partial occupation of other types of sites has also been detected. © 1995, American Vacuum Society. All rights reserved.},
note = {Issue: 3},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The Br/Si(211)2×1 interface was investigated using the x-ray standing wave technique. Three different Bragg reflections [(111), (220) and (422)] were used to determine the adsorption sites following a triangulation method. In all the interfaces prepared, Br adsorption reverted the 2×1 substrate reconstruction to 1×1. Br atoms occupy different sites depending on the preparation conditions: The conventional atop site of the [111]-like terraces of the surface, and also along the unsaturated dangling bonds of the [100]-like steps present at the surface. A partial occupation of other types of sites has also been detected. © 1995, American Vacuum Society. All rights reserved.
1870.
Panin, G. N.; Dutta, P. S.; Piqueras, J.; Dieguez, E.
P- to n-type conversion in GaSb by ion beam milling Journal Article
In: Applied Physics Letters, vol. 67, pp. 3584, 1995.
@article{panin_p-_1995,
title = {P- to n-type conversion in GaSb by ion beam milling},
author = {G. N. Panin and P. S. Dutta and J. Piqueras and E. Dieguez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0004297005&doi=10.1063%2f1.115325&partnerID=40&md5=6d58c4f0cc16a5eb67c97d77be15a397},
doi = {10.1063/1.115325},
year = {1995},
date = {1995-01-01},
journal = {Applied Physics Letters},
volume = {67},
pages = {3584},
abstract = {Inversion in conductivity type of GaSb from p- to n- has been observed as a result of argon ion beam milling. Electron beam induced current (EBIC) measurements have been employed for detecting the type conversion. Enhancement in the luminescence intensity is seen after ion beam treatment. The type conversion is proposed to occur due to a combined effect of generation of native donors and gettering of native acceptors originally present in the as-grown samples.© 1995 American Institute of Physics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Inversion in conductivity type of GaSb from p- to n- has been observed as a result of argon ion beam milling. Electron beam induced current (EBIC) measurements have been employed for detecting the type conversion. Enhancement in the luminescence intensity is seen after ion beam treatment. The type conversion is proposed to occur due to a combined effect of generation of native donors and gettering of native acceptors originally present in the as-grown samples.© 1995 American Institute of Physics.
1871.
Soriano, L.; Abbate, M.; Faber, J.; Morant, C.; Sanz, J. M.
The electronic structure of ZrO2: Band structure calculations compared to electron and x-ray spectra Journal Article
In: Solid State Communications, vol. 93, no. 8, pp. 659–665, 1995.
@article{soriano_electronic_1995,
title = {The electronic structure of ZrO2: Band structure calculations compared to electron and x-ray spectra},
author = {L. Soriano and M. Abbate and J. Faber and C. Morant and J. M. Sanz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0029244892&doi=10.1016%2f0038-1098%2894%2900882-5&partnerID=40&md5=a989333313f963a155d30ef34a55b7cc},
doi = {10.1016/0038-1098(94)00882-5},
year = {1995},
date = {1995-01-01},
journal = {Solid State Communications},
volume = {93},
number = {8},
pages = {659–665},
abstract = {We present and discuss band-structure calculations of ZrO2 in the cubic phase calculated by means of the Localized-Spherical-Waves (LSW) method with an extended basis set. The results obtained are in agreement with previous calculations and confirm a large covalent contribution to the bonding in ZrO2. The results are also compared to x-ray and electron spectra showing an overall good agreement between theory and experiment. In particular, the calculations reproduce well the distribution of the spectral weight and the magnitude of the band gap and the crystal-field splitting. © 1995.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present and discuss band-structure calculations of ZrO2 in the cubic phase calculated by means of the Localized-Spherical-Waves (LSW) method with an extended basis set. The results obtained are in agreement with previous calculations and confirm a large covalent contribution to the bonding in ZrO2. The results are also compared to x-ray and electron spectra showing an overall good agreement between theory and experiment. In particular, the calculations reproduce well the distribution of the spectral weight and the magnitude of the band gap and the crystal-field splitting. © 1995.
1872.
Morant, C.; Fernández, A.; González-Elipe, A. R.; Soriano, L.; Stampfl, A.; Bradshaw, A. M.; Sanz, J. M.
Electronic structure of stoichiometric and Ar+-bombarded ZrO2 determined by resonant photoemission Journal Article
In: Physical Review B, vol. 52, no. 16, pp. 11711–11720, 1995.
@article{morant_electronic_1995,
title = {Electronic structure of stoichiometric and Ar+-bombarded ZrO2 determined by resonant photoemission},
author = {C. Morant and A. Fernández and A. R. González-Elipe and L. Soriano and A. Stampfl and A. M. Bradshaw and J. M. Sanz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000450770&doi=10.1103%2fPhysRevB.52.11711&partnerID=40&md5=21c473dde17b85642f7597357b8568f9},
doi = {10.1103/PhysRevB.52.11711},
year = {1995},
date = {1995-01-01},
journal = {Physical Review B},
volume = {52},
number = {16},
pages = {11711–11720},
abstract = {The electronic properties of thermally grown ZrO2 thin films before and after Ar+ bombardment have been studied with resonant photoemission spectroscopy using synchrotron radiation. For stoichiometric ZrO2 thin films the experimental valence-band spectra are in good agreement with the calculated density of states for bulk ZrO2. For both stoichiometric and Ar+-bombarded ZrO2 thin films, resonant photoemission from the valence band was observed when the photon energy was swept through the Zr 4p→4d transition energy. The resonant profile was found to exhibit a maximum at hν=39 eV, followed by a second well-resolved broad maximum around 50 eV. The feature at 39 eV is consistent with resonant enhancement of the Zr 4d states and has been used to identify those regions of the valence band with an important Zr 4d admixture. The results are in good agreement with the calculated Zr 4d partial density of states. The intensity increase observed at hν∼45-50 eV is found to be associated with the nonbonding region of the valence band, although a proper interpretation is needed. In addition, it was found that Ar+ bombardment induces electronic states in the band-gap region and changes in the O 2p valence band. Three distinct emission bands were identified in the band gap as a function of the Ar+ dose. They are associated with the formation of oxygen vacancies and mixed oxidation states due to preferential sputtering of the oxygen atoms. Resonant photoemission of these Ar+-bombarded films demonstrates both the cationic character of the band-gap states and the increase of the cationic contribution to the O 2p valence band. © 1995 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The electronic properties of thermally grown ZrO2 thin films before and after Ar+ bombardment have been studied with resonant photoemission spectroscopy using synchrotron radiation. For stoichiometric ZrO2 thin films the experimental valence-band spectra are in good agreement with the calculated density of states for bulk ZrO2. For both stoichiometric and Ar+-bombarded ZrO2 thin films, resonant photoemission from the valence band was observed when the photon energy was swept through the Zr 4p→4d transition energy. The resonant profile was found to exhibit a maximum at hν=39 eV, followed by a second well-resolved broad maximum around 50 eV. The feature at 39 eV is consistent with resonant enhancement of the Zr 4d states and has been used to identify those regions of the valence band with an important Zr 4d admixture. The results are in good agreement with the calculated Zr 4d partial density of states. The intensity increase observed at hν∼45-50 eV is found to be associated with the nonbonding region of the valence band, although a proper interpretation is needed. In addition, it was found that Ar+ bombardment induces electronic states in the band-gap region and changes in the O 2p valence band. Three distinct emission bands were identified in the band gap as a function of the Ar+ dose. They are associated with the formation of oxygen vacancies and mixed oxidation states due to preferential sputtering of the oxygen atoms. Resonant photoemission of these Ar+-bombarded films demonstrates both the cationic character of the band-gap states and the increase of the cationic contribution to the O 2p valence band. © 1995 The American Physical Society.
1873.
Aliev, F. G.; Mfarrej, H. El; Vieira, S.; Villar, R.; Martinez, J. L.
Non-linear susceptibility in u0.9tho.1be13: Evidence of a transition from a paramagnetic to a quadrupolar kondo ground state Journal Article
In: EPL, vol. 32, no. 9, pp. 765–770, 1995.
@article{aliev_non-linear_1995,
title = {Non-linear susceptibility in u0.9tho.1be13: Evidence of a transition from a paramagnetic to a quadrupolar kondo ground state},
author = {F. G. Aliev and H. El Mfarrej and S. Vieira and R. Villar and J. L. Martinez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958463177&doi=10.1209%2f0295-5075%2f32%2f9%2f011&partnerID=40&md5=9e8793021fd575e400d12941d7974bc0},
doi = {10.1209/0295-5075/32/9/011},
year = {1995},
date = {1995-01-01},
journal = {EPL},
volume = {32},
number = {9},
pages = {765–770},
abstract = {We test the quadrupolar Kondo scenario in U0.9 Th01 Be13by measurements of the non-linear susceptibility. We found our non-linear-susceptibility data to be consistent with a transition below T textasciitilde 6 K from a magnetic (f3) to a quadrupolar (f2) doublet ground state of the U atom. © 1995 IOP Publishing Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We test the quadrupolar Kondo scenario in U0.9 Th01 Be13by measurements of the non-linear susceptibility. We found our non-linear-susceptibility data to be consistent with a transition below T textasciitilde 6 K from a magnetic (f3) to a quadrupolar (f2) doublet ground state of the U atom. © 1995 IOP Publishing Ltd.
1874.
Aliev, F. G.; Mfarrej, H. El; Vieira, S.; Villar, R.
Anomalous ground state of U0.9Th0.1Be13: Temperature dependence of the resistivity and magnetoresistance Journal Article
In: Solid State Communications, vol. 91, no. 10, pp. 775–778, 1994.
@article{aliev_anomalous_1994,
title = {Anomalous ground state of U0.9Th0.1Be13: Temperature dependence of the resistivity and magnetoresistance},
author = {F. G. Aliev and H. El Mfarrej and S. Vieira and R. Villar},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028496389&doi=10.1016%2f0038-1098%2894%2990646-7&partnerID=40&md5=2406ab575f79ca2fd9d0e90e25c61aa1},
doi = {10.1016/0038-1098(94)90646-7},
year = {1994},
date = {1994-01-01},
journal = {Solid State Communications},
volume = {91},
number = {10},
pages = {775–778},
abstract = {We have studied the transport and magnetotransport properties of U0.9Th0.1Be13. In this compound, the realization of a non-Fermi liquid ground state corresponding to the two channel Kondo effect (TCKE) was recently suggested from the heat capacity data. We have observed for the first time, that the anomalous temperature dependence of the thermodynamic properties were supplemented by a linear in a square root on T coordinates temperature dependence of electrical resistivity, in agreement with theoretical predictions for the TCKE. The magnetoresistance, measured in fields up to 11T, was found to be small and negative for T>5K, changing to small and positive (of about 1%) below 3K. © 1994.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have studied the transport and magnetotransport properties of U0.9Th0.1Be13. In this compound, the realization of a non-Fermi liquid ground state corresponding to the two channel Kondo effect (TCKE) was recently suggested from the heat capacity data. We have observed for the first time, that the anomalous temperature dependence of the thermodynamic properties were supplemented by a linear in a square root on T coordinates temperature dependence of electrical resistivity, in agreement with theoretical predictions for the TCKE. The magnetoresistance, measured in fields up to 11T, was found to be small and negative for T>5K, changing to small and positive (of about 1%) below 3K. © 1994.
1875.
Soriano, L.; Abbate, M.; Alders, D.; Sanz, J. M.
The bremsstrahlung isochromat spectra of d0 transition-metal oxides Journal Article
In: Solid State Communications, vol. 91, no. 7, pp. 551–554, 1994.
@article{soriano_bremsstrahlung_1994,
title = {The bremsstrahlung isochromat spectra of d0 transition-metal oxides},
author = {L. Soriano and M. Abbate and D. Alders and J. M. Sanz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028485382&doi=10.1016%2f0038-1098%2894%2990372-7&partnerID=40&md5=2c518a8d588c2a7bad44ed9bdfe5e746},
doi = {10.1016/0038-1098(94)90372-7},
year = {1994},
date = {1994-01-01},
journal = {Solid State Communications},
volume = {91},
number = {7},
pages = {551–554},
abstract = {We present and discuss the bremsstrahlung isochromat spectra (BIS) of four d0 transition-metal oxides; namely ZrO2, HfO2, Nb2O5, and Ta2O5. The spectra are related to the density of unoccupied states in the conduction band. They give directly the magnitude of the crystal-field splitting and the dispersion of the metal-d bands. The trends observed in the spectra are discussed and compared to those found in the O 1s x-ray absorption spectra (XAS) of the same materials. © 1994.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present and discuss the bremsstrahlung isochromat spectra (BIS) of four d0 transition-metal oxides; namely ZrO2, HfO2, Nb2O5, and Ta2O5. The spectra are related to the density of unoccupied states in the conduction band. They give directly the magnitude of the crystal-field splitting and the dispersion of the metal-d bands. The trends observed in the spectra are discussed and compared to those found in the O 1s x-ray absorption spectra (XAS) of the same materials. © 1994.
1876.
Prieto, P.; Galán, L.; Sanz, J. M.
Interaction of oxygen with ZrN at room temperature: An XPS study Journal Article
In: Surface and Interface Analysis, vol. 21, no. 6-7, pp. 395–399, 1994.
@article{prieto_interaction_1994,
title = {Interaction of oxygen with ZrN at room temperature: An XPS study},
author = {P. Prieto and L. Galán and J. M. Sanz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028444356&doi=10.1002%2fsia.740210612&partnerID=40&md5=06556dc2e6c9b4de298ad1677a161e18},
doi = {10.1002/sia.740210612},
year = {1994},
date = {1994-01-01},
journal = {Surface and Interface Analysis},
volume = {21},
number = {6-7},
pages = {395–399},
abstract = {Quantitative XPS has been used to characterize the interaction of oxygen with ZrN at room temperature. The results indicate that ZrN remains unaffected for oxygen exposures <104 L at oxygen pressures <10−7 Torr. However, higher oxygen exposures at higher pressures cause the formation of an oxynitride (ZrN0.5O0.5) and ZrO2. At 108 L saturation is reached, with the formation of an oxidized layer that is 17 Å thick formed by 5 Å of ZrO2 and an interface layer (12 Å thick) of average composition ZrN0.5O0.5. Analysis of the core levels and valence band of the oxynitride demonstrates its ionic character as well as its insulating properties in comparison with metallic ZrN. Copyright © 1994 John Wiley & Sons Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Quantitative XPS has been used to characterize the interaction of oxygen with ZrN at room temperature. The results indicate that ZrN remains unaffected for oxygen exposures <104 L at oxygen pressures <10−7 Torr. However, higher oxygen exposures at higher pressures cause the formation of an oxynitride (ZrN0.5O0.5) and ZrO2. At 108 L saturation is reached, with the formation of an oxidized layer that is 17 Å thick formed by 5 Å of ZrO2 and an interface layer (12 Å thick) of average composition ZrN0.5O0.5. Analysis of the core levels and valence band of the oxynitride demonstrates its ionic character as well as its insulating properties in comparison with metallic ZrN. Copyright © 1994 John Wiley & Sons Ltd.
1877.
Ruiz, A.; Mestres, N.; Calleja, J. M.; Wagner, J.; Briones, F.
Growth and characterization of Al1-yInyAs/Ga 1-xInxAs strained multiple quantum wells Journal Article
In: Journal of Applied Physics, vol. 75, no. 9, pp. 4496–4500, 1994.
@article{ruiz_growth_1994,
title = {Growth and characterization of Al1-yInyAs/Ga 1-xInxAs strained multiple quantum wells},
author = {A. Ruiz and N. Mestres and J. M. Calleja and J. Wagner and F. Briones},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36449000797&doi=10.1063%2f1.355940&partnerID=40&md5=df7b6704d9f3f1287ad9414e3f78c123},
doi = {10.1063/1.355940},
year = {1994},
date = {1994-01-01},
journal = {Journal of Applied Physics},
volume = {75},
number = {9},
pages = {4496–4500},
abstract = {Highly strained Al1-yInyAs/Ga1-xIn xAs multiple quantum wells have been grown by atomic layer molecular beam epitaxy on [001]-GaAs substrates. Raman scattering and x-ray diffraction techniques have been used to determine layer composition and strain for a wide range of In concentration (0≤x≤0.44). When a thick buffer layer of AlInAs is used, commensurate growth of the quantum wells takes place if the In content of the barriers equals that of the buffer layer. Then the strain is only accumulated in the wells. The GaInAs wells can be either under biaxial tension or compression depending on the relative In content in wells and barriers.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Highly strained Al1-yInyAs/Ga1-xIn xAs multiple quantum wells have been grown by atomic layer molecular beam epitaxy on [001]-GaAs substrates. Raman scattering and x-ray diffraction techniques have been used to determine layer composition and strain for a wide range of In concentration (0≤x≤0.44). When a thick buffer layer of AlInAs is used, commensurate growth of the quantum wells takes place if the In content of the barriers equals that of the buffer layer. Then the strain is only accumulated in the wells. The GaInAs wells can be either under biaxial tension or compression depending on the relative In content in wells and barriers.
1878.
Aliev, F. G.; Villar, R.; Vieira, S.; Levanyuk, A. P.; Scolozdra, R. V.
Thermal expansion of the disordered conductors MNiSn (M=Ti,Zr,Hf) Journal Article
In: Physical Review B, vol. 50, no. 24, pp. 17881–17885, 1994.
@article{aliev_thermal_1994,
title = {Thermal expansion of the disordered conductors MNiSn (M=Ti,Zr,Hf)},
author = {F. G. Aliev and R. Villar and S. Vieira and A. P. Levanyuk and R. V. Scolozdra},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0242283793&doi=10.1103%2fPhysRevB.50.17881&partnerID=40&md5=b2e5b22ef48b832bcff38c7cc0b2fabf},
doi = {10.1103/PhysRevB.50.17881},
year = {1994},
date = {1994-01-01},
journal = {Physical Review B},
volume = {50},
number = {24},
pages = {17881–17885},
abstract = {We report on the behavior of the low-temperature transport properties and thermal expansion of the intermetallic compounds MNiSn (M=Ti,Zr,Hf) through the metal-insulator transition. In the low-conductivity samples [102 (cm)-1] situated on the metallic side, the conductivity varies at T<10 K as 0+A0 T, which may be ascribed to a Coulomb-interaction correction. For the same temperature interval an anomalous negative thermal expansion with negative values approximately proportional to the degree of interaction, evaluated from the conductivity, was observed. A discussion of the possible effect of electron-electron interaction on the electron thermal expansion based on the results of Altshuler and Aronov is also presented. © 1994 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report on the behavior of the low-temperature transport properties and thermal expansion of the intermetallic compounds MNiSn (M=Ti,Zr,Hf) through the metal-insulator transition. In the low-conductivity samples [102 (cm)-1] situated on the metallic side, the conductivity varies at T<10 K as 0+A0 T, which may be ascribed to a Coulomb-interaction correction. For the same temperature interval an anomalous negative thermal expansion with negative values approximately proportional to the degree of interaction, evaluated from the conductivity, was observed. A discussion of the possible effect of electron-electron interaction on the electron thermal expansion based on the results of Altshuler and Aronov is also presented. © 1994 The American Physical Society.
1879.
Yubero, F.; Sanz, J. M.; Trigo, J. F.; Elizalde, E.; Tougaard, S.
Quantitative analysis of REELS spectra of ZrO2: Determination of the dielectric loss function and inelastic mean free paths Journal Article
In: Surface and Interface Analysis, vol. 22, no. 1-12, pp. 124–128, 1994.
@article{yubero_quantitative_1994,
title = {Quantitative analysis of REELS spectra of ZrO2: Determination of the dielectric loss function and inelastic mean free paths},
author = {F. Yubero and J. M. Sanz and J. F. Trigo and E. Elizalde and S. Tougaard},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028463249&doi=10.1002%2fsia.740220130&partnerID=40&md5=4ee42c9de593c39f0b6e5100289dcbdc},
doi = {10.1002/sia.740220130},
year = {1994},
date = {1994-01-01},
journal = {Surface and Interface Analysis},
volume = {22},
number = {1-12},
pages = {124–128},
abstract = {The dielectric loss function of ZrO2 over 0–80 eV has been determined from a quantitative analysis of reflection electron energy loss spectra (REELS) at different primary energies. From this, the inelastic electron mean free path for 200–2000 eV electrons in ZrO2 has been calculated. The inelastic mean free path (IMPF) is found to depend on the depth from which the electron is backscattered. For great depths, the IMFP approaches a constant value which is the same as that which would be obtained within a model that ignores the effects of the surface. The derived IMFP values have been compared to different formulae presented in the literature and the TPP2 formula due to Tanuma et al. is found to give the best agreement with the present results. Copyright © 1994 John Wiley & Sons Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The dielectric loss function of ZrO2 over 0–80 eV has been determined from a quantitative analysis of reflection electron energy loss spectra (REELS) at different primary energies. From this, the inelastic electron mean free path for 200–2000 eV electrons in ZrO2 has been calculated. The inelastic mean free path (IMPF) is found to depend on the depth from which the electron is backscattered. For great depths, the IMFP approaches a constant value which is the same as that which would be obtained within a model that ignores the effects of the surface. The derived IMFP values have been compared to different formulae presented in the literature and the TPP2 formula due to Tanuma et al. is found to give the best agreement with the present results. Copyright © 1994 John Wiley & Sons Ltd.
1880.
Calle, F.; Calleja, J. M.; Tejedor, C.; Briones, F.; Miguel, J. L.; Ploog, K.
Resonant raman scattering in GaAsAlAs coupled double wells Journal Article
In: Surface Science, vol. 228, no. 1-3, pp. 176–179, 1990.
@article{calle_resonant_1990,
title = {Resonant raman scattering in GaAsAlAs coupled double wells},
author = {F. Calle and J. M. Calleja and C. Tejedor and F. Briones and J. L. Miguel and K. Ploog},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-44949289363&doi=10.1016%2f0039-6028%2890%2990285-G&partnerID=40&md5=30aa0d23083ce98fb91a1a8ef194fcd2},
doi = {10.1016/0039-6028(90)90285-G},
year = {1990},
date = {1990-01-01},
journal = {Surface Science},
volume = {228},
number = {1-3},
pages = {176–179},
abstract = {GaAsAlAs multiquantum wells having a thin AlAs spike in the middle of each well have been studied by resonant Raman scattering. Transitions to both Γ-like and X-like conduction bands are observed. AlAs- and GaAs-like interface modes (IF) have also been observed, whose frequency changes with the spike width. This effect is explained by a generalized electrostatic model for IF modes. Finally, the AlAs LO1 mode confined in the spike has been observed, showing a resonance at electronic transitions of the GaAs wells. © 1990.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
GaAsAlAs multiquantum wells having a thin AlAs spike in the middle of each well have been studied by resonant Raman scattering. Transitions to both Γ-like and X-like conduction bands are observed. AlAs- and GaAs-like interface modes (IF) have also been observed, whose frequency changes with the spike width. This effect is explained by a generalized electrostatic model for IF modes. Finally, the AlAs LO1 mode confined in the spike has been observed, showing a resonance at electronic transitions of the GaAs wells. © 1990.
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Being a member of the Nicolás Cabrera Institute (INC) entails the commitment to include the institutional affiliation in all scientific publications resulting from research activities carried out within the INC framework.
The affiliation that must appear in the publications is:
Instituto Nicolás Cabrera (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain