Papers
1821.
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.
1822.
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.
1823.
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.
1824.
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.
1825.
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.
1826.
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.
1827.
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.
1828.
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.