High pressure magnetic phase diagram of an antiferromagnetic Cr+0.50 at.% Re alloy single crystal

Abstract

The pressure–temperature magnetic phase diagram of a Cr+0.50 at.% Re alloy single crystal has been obtained from high pressure ultrasonic wave velocity measurements. A triple point exists on the magnetic phase diagram where the incommensurate (I) and commensurate (C) spin-density-wave (SDW) phases coexist with the paramagnetic (P) phase. The ISDW–CSDW phase transition is a first-order transition while the CSDW–P and ISDW–P Néel transitions are continuous. Both the ISDW–CSDW/CSDW–ISDW and CSDW–P phase lines are nonlinear with exceptionally large pressure derivatives near the triple point pressure. Thermal expansion measurements on the crystal together with the high pressure measurements give a latent heat of 13.7 J mol −1 associated with the first-order ISDW–CSDW phase transition. The temperature dependence of the magnetovolume, Δ ω, has been observed to fit the equation |Δ ω|= A 0+ A 1 T 2+ A 2 T 4 fairly well in the CSDW phase.