High-field magnetostriction of the valence-fluctuating compoundYbInCu4

Abstract

The $\mathrm{Yb}\mathrm{In}{\mathrm{Cu}}_{4}$ compound undergoes a first-order valence transition from the intermediate valence state to the trivalent state with increasing either temperature or magnetic field. We have measured the magnetization and magnetostriction in pulsed magnetic fields up to $40\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ in the temperature range $4.2--120\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. It was found that the volume magnetostriction at the field-induced valence transition $\ensuremath{\Delta}\ensuremath{\omega}=\ensuremath{-}4.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ corresponds well to the spontaneous volume change at the temperature-induced transition. The magnetovolume coupling constant is negative. Its absolute value is rather large for the low-temperature mixed-valence state, but strongly suppressed in the high-temperature local-moment state. A considerable anisotropic magnetostriction is found for both low-temperature and high-temperature phases. The temperature and field variations of the anisotropic magnetostriction are described in terms of a single-ion model of the interaction of an anisotropic $4f$ shell of Yb ion with the crystal electric field.