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

TL;DR

This study investigates how the glass transition temperature (Tg) in a magnetic glass varies with magnetic field, providing visual evidence of devitrification and linking the slope of Tg vs magnetic field to Le Chatelier's Principle.

Contribution

It presents direct mesoscopic evidence of devitrification in a magnetic glass and elucidates the relationship between Tg and magnetic field based on thermodynamic principles.

Findings

Visual evidence of devitrification from antiferromagnetic-insulating to ferromagnetic-metallic phase.

The slope of Tg versus magnetic field is governed by Le Chatelier's Principle.

The behavior of Tg with magnetic field is similar during warming and isothermal field increase.

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 $Pr_{0.5}Ca_{0.5}Mn_{0.975}Al_{0.025}O_3$ 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.