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Phonon anomalies at the valence transition of SmS : An inelasticX-ray scattering study under pressure

S. Raymond·J. P. Rueff·M. D'Astuto·D. Braithwaite·M. Krisch·J. Flouquet
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Abstract

The phonon dispersion curve of SmS under pressure was studied by inelastic x-ray scattering around the pressure-induced valence transition. A significant softening of the longitudinal acoustic modes propagating along the [111] direction was observed spanning a wide $q$ region from ($\frac{2π}{3a},\frac{2π}{3a},\frac{2π}{3a}$) up to the zone boundary as SmS becomes metallic. The largest softening occurs at the zone boundary and stays stable up to the highest measured pressure of 80 kbar while a gradual hardening of the low $q$ modes simultaneously appears. This phonon spectrum indicates favorable conditions for the emergence of pressure-induced superconductivity in SmS.

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S. Raymond, J. P. Rueff, M. D'Astuto, D. Braithwaite, M. Krisch, J. Flouquet. 2002-04-19. Phonon anomalies at the valence transition of SmS : An inelasticX-ray scattering study under pressure. https://doi.org/10.1103/physrevb.66.220301

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