Unconventional Magnetization of Fe3O4 Thin Film Grown on Amorphous SiO2 Substrate

TL;DR

This study reports unconventional magnetic properties in high-quality Fe3O4 thin films grown on amorphous SiO2, showing higher Verwey transition temperature and out-of-plane magnetization, linked to substrate-induced electronic interactions.

Contribution

It reveals that Fe3O4 thin films on amorphous SiO2 exhibit enhanced and directionally entangled magnetic properties due to substrate effects, a novel finding in thin film magnetism.

Findings

Verwey transition temperature around 140K, higher than bulk

Out-of-plane magnetization exceeds in-plane magnetization

Enhanced Coulomb correlation U and exchange J due to substrate coupling

Abstract

High quality single crystal Fe3O4 thin films with (111) orientation had been prepared on amorphous SiO2 substrate by pulsed laser deposition. The magnetization properties of the films are found to be highly unconventional. The Verwey transition temperature derived from the magnetization jump is around 140K, which is higher than the bulk value and it can be slightly suppressed by out-plane magnetic field; the out-of-plane magnetization, which is unexpectedly higher than the in-plane value, is also significantly increased as compared with the bulk value. Our findings suggest that the local Coulomb correlation U and the effective ferromagnetic exchange interaction J of Fe 3d electrons are both dramatically strengthened and out-of-plane directionally entangled by the unusual coupling between Fe3O4 thin film and the amorphous SiO2 substrate.