Thermal expansion and magnetostriction of superconducting URu2Si2

Abstract

Dilatation measurements have been performed on a single-crystalline sample of the heavy-fermion superconductor URu2Si2 (Tc=1.2 K). Thermal-expansion measurements in combination with specific-heat data reveal a thermal electronic Grüneisen parameter of ΓT=27. A comparison with the magnetic electronic Grüneisen parameter derived from the magnetostriction, ΓB=26, points to a single energy scale. The measured magnetostriction is strongly anisotropic with a peculiar hysteresis. Close to the upper critical field, a change of sign in the magnetostrictive hysteresis is observed.