Mediating exchange bias by Verwey transition in CoO/Fe3O4 thin film

TL;DR

This study demonstrates that the exchange bias effect in CoO/Fe3O4 thin films can be controlled by the Verwey transition in Fe3O4, leading to enhanced magnetic properties near the transition temperature.

Contribution

The paper reveals how the Verwey transition in Fe3O4 can be used to tune the exchange bias effect in CoO/Fe3O4 thin films, introducing a new method for magnetic property control.

Findings

Exchange bias field peaks near the Verwey transition temperature.

Magnetocrystalline anisotropy increases sharply at the transition.

Coercivity is significantly enhanced in the bilayer structure.

Abstract

We report the tunability of the exchange bias effect by the first-order metal-insulator transition (known as the Verwey transition) of Fe3O4 in CoO (5 nm)/Fe3O4 (40 nm)/MgO (001) thin film. In the vicinity of the Verwey transition, the exchange bias field is substantially enhanced because of a sharp increase in magnetocrystalline anisotropy constant from high-temperature cubic to lowtemperature monoclinic structure. Moreover, with respect to the Fe3O4 (40 nm)/MgO (001) thin film, the coercivity field of the CoO (5 nm)/Fe3O4 (40 nm)/MgO (001) bilayer is greatly increased for all the temperature range, which would be due to the coupling between Co spins and Fe spins across the interface.