Regular Article
Influence of the Mixed-Valences State on the Magnetic Excitation Spectrum of SmB6-Based Compounds

https://doi.org/10.1006/jssc.1997.7447Get rights and content

Abstract

A series of experimental studies of the dynamical magnetic response of Sm in SmB6-based mixed-valence (MV) systems has been carried out by inelastic neutron scattering on poly- and single-crystalline, double-isotopic (154Sm,11B), samples. In addition to two strongly damped high-energy peaks associated with the inter-multiplet transitions of Sm2+and Sm3+, pure SmB6exhibits a very specific low-energy excitation at 14 meV. These features can be ascribed to the formation of the MV ground state. To study the effect of a variation of the average valenceνon the magnetic excitation spectra, solid solutions have been studied in which 2+ or 3+ ions are substituted for Sm. The intensities of the inter-multiplet excitations change roughly in accordance with the variation ofν. Systematic changes are observed in the position of the low-energy peak and in theQandTdependences of its intensity, Further information concerning the energy, anisotropy, and theQandTdependences of the low-energy excitation was obtained from triple-axis experiments on single crystals of Sm1−xLaxB6(x=0.10, 0.22) at ambient pressure and SmB6atP=0.5 GPa. The transformations observed in the low-energy part of the spectra suggest a relation between the average valence and the degree of delocalization (or hybridization strength) for the “loosely bound”f-electron state formed around the Sm ion, which is a characteristic feature of the MV ground state.

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