The spontaneous exchange bias effect on La$_{1.5}$Ba$_{0.5}$CoMnO$_{6}$

TL;DR

This study investigates the spontaneous exchange bias effect in La$_{1.5}$Ba$_{0.5}$CoMnO$_{6}$, revealing its temperature dependence, enhancement under field cooling, and modeling through relaxation of spin-glass-like moments.

Contribution

It provides a detailed experimental analysis of the spontaneous exchange bias in a specific re-entrant cluster glass material and applies a new model to describe the observed asymmetry.

Findings

Spontaneous exchange bias appears below 20 K.

Maximum bias observed at 75 kOe magnetic field.

Field cooling significantly enhances the exchange bias.

Abstract

La$_{1.5}$Ba$_{0.5}$CoMnO$_{6}$ is a re-entrant cluster glass material exhibiting a robust negative exchange bias (EB) effect even after being cooled from an unmagnetized state down to low temperature in zero magnetic field. Here we thoroughly investigate this phenomena by performing magnetization as a function of applied field [$M(H)$] measurements at several different temperatures and maximum applied magnetic fields ($H_m$). The spontaneous EB (SEB) effect is observed below 20 K, and shows a maximum value for $H_m$ = 75 kOe. The effect is greatly enhanced when the $M(H)$ curves are measured after the system is cooled in the presence of a magnetic field. The asymmetry of the $M(H)$ curves here investigated can be well described by a recently proposed model based on the unconventional relaxation of the SG-like moments during the hysteresis cycle.