Exchange Bias Induced by the Fe3O4 Verwey transition

TL;DR

This study demonstrates a novel link between the Verwey transition in Fe3O4 and the emergence of exchange bias and vertical magnetization shifts in V2O3/NiFe thin film systems, revealing temperature-dependent magnetic phenomena.

Contribution

It uncovers a direct relationship between the Verwey transition in Fe3O4 and exchange bias effects in V2O3-based heterostructures, a novel insight into magnetic phase interactions.

Findings

Exchange bias appears only below 120 K, coinciding with the Verwey transition.

A large vertical magnetization shift of up to 60% was observed.

The effects disappear above 120 K, linking them to the Verwey transition.

Abstract

We present a study of the exchange bias in different configurations of V2O3 thin films with ferromagnetic layers. The exchange bias is accompanied by a large vertical shift in the magnetization. These effects are only observed when V2O3 is grown on top of Ni80Fe20 permalloy. The magnitude of the vertical shift is as large as 60% of the total magnetization which has never been reported in any system. X-Ray diffraction studies show that the growth conditions promote the formation of a ferrimagnetic Fe3O4 interlayer. The change in the easy magnetization axis of Fe3O4 across the Verwey transition at 120 K is correlated with the appearance of exchange bias and vertical shift in magnetization. Both phenomena disappear above 120 K, indicating for the first time a direct relationship between the magnetic signature of the Verwey transition and exchange bias.