Anisotropic thermal expansion and evaluation of uniaxial pressure dependence of superconducting and magnetic transitions in ErNi2B2C

We present anisotropic thermal expansion measurements on single crystalline ErNi₂B₂C. All three, superconducting, antiferromagnetic and weak ferromagnetic phase transitions are unambiguously distinguished in the data. Anisotropic uniaxial pressure dependencies of the transitions are estimated based on the Ehrenfest relation, leading to a conclusion, in particular, that weak ferromagnetic states may be suppressed by small, order of few kbar, hydrostatic pressure. Additionally, magnetostriction is shown to be a useful probe for rich and complex H-T diagram in this material.