Phase Diagram of the Isotropic Antiferromagnet RbMnF3: Test of Scaling and Renormalization-Group Calculations

Abstract

The variation of the ordering temperature $T_c\mathrm{}\left(H\right)\mathrm{}$ of the (very nearly) isotropic antiferromagnet RbMn${\mathrm{F}}_3$ with magnetic field $H$ was determined from thermal expansion measurements in fields up to 180 kOe. With increasing $H$, $T_c\mathrm{}\left(H\right)\mathrm{}$ first increases, then reaches a maximum, and finally decreases. The bow-shaped phase boundary, in the $T-H$ plane, is well described by recent theories based on scaling and renormalization-group calculations.