Variation of T${}_g$ with magnetic field in a magnetic glass

Abstract

Glass-like arrest has recently been reported in various magnetic materials. As in structural glasses, the kinetics of a first-order transformation is arrested while retaining the higher-entropy phase as a non-ergodic state. We show visual mesoscopic evidence of the irreversible devitrification of the arrested antiferromagnetic-insulating phase in $P{r}_{0.5}C{a}_{0.5}M{n}_{0.975}A{l}_{0.025}{O}_3$ to its equilibrium ferromagnetic-metallic phase with isothermal increase of magnetic field, similar to its iso-field devitrification on warming. The slope of $T_g$ vs magnetic field in half-doped manganites is shown to have a sign governed by Le Chatelier's Principle.