Fe3O4 thin films: controlling and manipulating an elusive quantum material

TL;DR

This paper reports on the growth of high-quality Fe3O4 thin films with a sharp Verwey transition, and demonstrates the ability to tune this transition temperature using substrate selection and tensile strain, advancing spintronic material applications.

Contribution

It introduces a new substrate class enabling sharp Verwey transitions in Fe3O4 thin films and shows how to tune the transition temperature via strain engineering.

Findings

Achieved sharp Verwey transition in thin films comparable to bulk

Successfully increased transition temperature using tensile strain

Identified substrate conditions for high-quality Fe3O4 film growth

Abstract

Fe3O4 (magnetite) is one of the most elusive quantum materials and at the same time one of the most studied transition metal oxide materials for thin film applications. The theoretically expected half-metallic behavior generates high expectations that it can be used in spintronic devices. Yet, despite the tremendous amount of work devoted to preparing thin films, the enigmatic first order metal-insulator transition and the hall mark of magnetite known as the Verwey transition, is in thin films extremely broad and occurs at substantially lower temperatures as compared to that in high quality bulk single crystals. Here we have succeeded in finding and making a particular class of substrates that allows the growth of magnetite thin films with the Verwey transition as sharp as in the bulk. Moreover, we are now able to tune the transition temperature and, using tensile strain, increase it to substantially higher values than in the bulk.