Pressure Dependence of the Valence Phase Transition in YbInCu4.

Abstract

The valence phase transition of YbInCu4 has been investigated by neutron diffraction and high pressure experiments. Rietveld refinement of the crystal structure has showed that the transition occurs with no change in crystal symmetry in a temperature range of about 35-50 K. The transition temperature Tv decreases linearly at a rate of -17 K/GPa with increasing the pressure up to 1 GPa, above which it decreases much faster up to 1. 75GPa. By using the bulk modules of YbInCu4, a Gruneisen type parameter of η=dln (Tv) /dln (V (p) ), which represents the dependence of Tv on the volume V (p) is estimated as -64. This value of η is discussed in a relation to the Kondo volume collapse model for the α-γ transition of Ce metal.