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Type: Artigo de periódico
Title: Search for spin-lattice coupling mediated by itinerant electrons: Synchrotron x-ray diffraction and Raman scattering from GdAl(3)
Author: Garcia-Flores, AF
Malachias, A
Granado, E
Fisk, Z
Abstract: The coupling among the spin degree of freedom and the atomic displacements in intermetallic GdAl(3) was investigated by means of synchrotron x-ray diffraction and polarized Raman scattering. In this compound, the Gd 4f(7) shell is spherical and the spin-lattice coupling provides a fingerprint of the exchange mechanism and degree of magnetic correlations. X-ray diffraction shows nonresonant symmetry-forbidden charge Bragg peaks below the long-range magnetic ordering temperature T(N)=18 K, revealing a symmetry-lowering crystal lattice transition associated with Gd displacements, consistent with a Ruderman-Kittel-Kasuya-Yosida mechanism for the magnetic coupling. Raman scattering in fresh broken surfaces shows phonons with conventional frequency behavior, while naturally grown and polished surfaces present frequency anomalies below T*similar to 50 K. Such anomalies are possibly due to a modulation of the magnetic energy by the lattice vibrations in a strongly spin-correlated paramagnetic phase. Such interpretation implies that the spin-phonon coupling in metals may depend on the surface conditions. A fully spin-correlated state immediately above T(N) is inferred from our results in this frustrated system.
Country: EUA
Editor: Amer Physical Soc
Rights: aberto
Identifier DOI: 10.1103/PhysRevB.77.024414
Date Issue: 2008
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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