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642 results on '"Vettier C"'

1. Itinerant magnetism in Kondo crystal CeB6 as indicated by polarized neutron scattering

Author

Plakhty, V. P., Regnault, L. P., Goltsev, A. V., Gavrilov, S. V., Yakhou, F., Flouquet, J., Vettier, C., and Kunii, S.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

A magnetic Bragg reflection corresponding to the wave vector k13 = (2pi/a)[1/2,1/2,1/2] of the antiferro-quadrupolar ordering is found in CeB6 in zero magnetic field below the Neel temperature TN. Its intensity is two orders of magnitude weaker than those due to the basic magnetic structure [O. Zaharko et al., Phys. Rev. B 68, 214401 (2003)]. The peak has a width of the other Bragg reflections below TN, but widens abruptly at T = TN with simultaneous increase of intensity. Correlation length just above TN is of the order of 70 A. The peak intensity decreases to zero at T = 7 K with no visible anomaly at the antiferro-quadrupolar ordering temperature TQ = 3.3 K. The features of this magnetic ordering are typical for the itinerant magnetism with 5d electron of Ce3+ [Yu.S. Grushko et al., phys. stat. sol. (b) 128, 591 (1985)] being involved., Comment: 4 pages, 3 figures

Published
2004
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2. Shifting of the magnetic resonance peak to lower energy in the superconducting state of underdoped YBa_2Cu_3O_{6.8}

Author

Bourges, Ph., Regnault, L. P., Sidis, Y., Bossy, J., Burlet, P., Vettier, C., Henry, J. Y., and Couach, M.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Inelastic neutron scattering has been used to determine the dynamic spin fluctuations in an underdoped high temperature superconductor YBCO_{6.8} single crystal. The magnetic resonance, that occurs around 40 meV in overdoped samples, is shifted to a lower energy, E_r= 34 meV. A constant ratio, $E_r/ k_B T_C= 4.9 \pm 0.2$, almost independent of the doping level, is found. According to numerous theoretical approaches, this finding supports the idea that the resonance energy is proportional (approximately twice) to the superconducting gap., Comment: 8 pages, 3 figures, accepted in Europhysics Letter

Published
1997
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3. High energy spin excitations in YBa_2 Cu_3 O_{6.5}

Author

Bourges, Ph., Fong, H. F., Regnault, L. P., Bossy, J., Vettier, C., Milius, D. L., Aksay, I. A., and Keimer, B.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Inelastic neutron scattering has been used to obtain a comprehensive description of the absolute dynamical spin susceptibility $\chi'' (q,\omega)$ of the underdoped superconducting cuprate YBa_2 Cu_3 O_{6.5} ($T_c = 52 K$) over a wide range of energies and temperatures ($2 meV \leq \hbar \omega \leq 120 meV$ and $5K \leq T \leq 200K$). Spin excitations of two different symmetries (even and odd under exchange of two adjacent CuO_2 layers) are observed which, surprisingly, are characterized by different temperature dependences. The excitations show dispersive behavior at high energies., Comment: 15 pages, 5 figures

Published
1997
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25. Observation of orbital moment in NiO using magnetic x-ray scattering

Author

Neubeck, W., Vettier, C., Fernandez, V., Bergevin, F. de, and Giles, C.

Subjects
Magnetism -- Research, Rotational motion -- Research, X-rays -- Scattering, Physics
Abstract

A study was conducted to analyze orbital moment in NiO by exploiting the polarization dependence of nonresonant x-ray magnetic scattering. Azimuthal scans were carried out to examine the spin and orbital moments. Experimental results indicated that the orbital moment supports a critical function with a contribution of 17% of the total magnetization density. Findings also showed that spin and orbital moments were collinear.

Published
1999

38. Study of the hydrogen stability in evaporated amorphous Si1-xSnx:H (0< or = x< or = 0.2) alloys by neutron scattering and exodiffusion measurements

Author

Houssaini, S., Vergnat, M., Bruson, A., Marchal, G., and Vettier, C.

Subjects
Hydrogen -- Research, Scattering (Physics) -- Usage, Diffusion -- Usage, Stability -- Research, Alloys -- Research, Physics
Abstract

The effect of tin on the stability of hydrogen in evaporated amorphous hydrogenated Si1-xSn alloys was investigated using neutron scattering and exodiffusion analysis. The results showed that increased tin concentration led to a deterioration in the satbility of hydrogen. The alloys coevaporated on a substrate at liquid-nitrogen temperature exhibited porous characteristics. In addition, hydrogen desorbed at low temperatures.

Published
1993

43. Quantum energy gap in two quasi-one-dimensional S=1 Heisenberg antiferromagnets (invited).

Author

Renard, J. P., Verdaguer, M., Regnault, L. P., Erkelens, W. A. C., Rossat-Mignod, J., Ribas, J., Stirling, W. G., and Vettier, C.

Subjects
ANTIFERROMAGNETISM, SCATTERING (Physics), MAGNETISM, HAMILTONIAN systems
Abstract

Presents information on the findings of experimental studies on two quasi-one-dimensional Heisenberg antiferromagnets. Application of inelastic neutron scattering experiments; Effect of magnetic anisotropy on a Hamiltonian equation; Implication of a gap on the low temperature magnetic properties; Crystal structure of the antiferromagnets.

Published
1988
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