Anomalous coercivity enhancement with temperature and tunable exchange bias in Gd and Ti co-doped BiFeO$_3$ multiferroics

TL;DR

This study reveals that Gd and Ti co-doped BiFeO3 multiferroics exhibit increasing coercivity with temperature and tunable exchange bias, highlighting novel magnetic behaviors in these materials.

Contribution

It demonstrates temperature-dependent coercivity enhancement and tunable exchange bias in Gd and Ti co-doped BiFeO3, a novel magnetic property not previously reported.

Findings

Coercive fields increase with temperature.

Exchange bias effect observed and tunable up to 250 K.

Higher coercivity and remanent magnetization in specific compositions.

Abstract

We have investigated the effect of temperature on magnetic properties of Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20) multiferroic system. Unexpectedly, the coercive fields ($H_{c}$) of this multiferroic system increased with increasing temperature. The coercive fields and remanent magnetization were higher over a wide range of temperatures in sample x = 0.10 i.e. in sample having composition Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$ than those of x = 0.00 and 0.20 compositions. Therefore, we have carried out temperature dependent magnetization experiments extensively for sample x = 0.10. The magnetic hysteresis loops at different temperatures exhibit an asymmetric shift towards the magnetic field axes which indicate the presence of exchange bias effect in this material system. The hysteresis loops were also carried out at temperatures 150 K and 250 K by cooling down the sample from 300 K in various cooling magnetic fields ($H_{cool}$). The exchange bias field ($H_{EB}$) values increased with $H_{cool}$ and decreased with temperature. The $H_{EB}$ values were tunable by field cooling at temperatures up to 250 K.