Giant exchange bias in a single-phase magnet with two magnetic sublattices

TL;DR

This paper reports a novel bulk exchange bias effect in a single-phase magnet with two magnetic sublattices, demonstrating a giant shift in coercive field due to internal sublattice coupling, unlike traditional interfacial exchange bias.

Contribution

It introduces a new bulk exchange bias mechanism in a single-phase material, expanding understanding beyond interfacial effects.

Findings

Giant exchange bias of a few Tesla observed at low temperatures.

Exchange bias depends on cooling magnetic field and exhibits training effects.

The phenomenon is explained by coupling between magnetic sublattices.

Abstract

Exchange bias phenomenon is generally ascribed to the exchange coupling at the interfaces between ferromagnetic and antiferromagnetic layers. Here, we propose a bulk form of exchange bias in a single-phase magnet where the coupling between two magnetic sublattices induces a significant shift of the coercive field after a field cooling. Our experiments in a complicated magnet YbFe2O4 demonstrate a giant exchange bias at low temperature when the coupling between the Yb3+ and Fe2+/Fe3+ sublattices take places. The cooling magnetic field dependence and the training effect of exchange bias are consistent with our model. In strong contrast to conventional interfacial exchange bias, this bulk form of exchange bias can be huge, reaching the order of a few Tesla.