Promoting the magnetic exchanges in PLD deposited strained films of FeV2O4 thin films

Abstract Transition metal complex oxides are remarkable for the richness of tunable physical properties their strongly correlated electrons allow. We have undertaken the pulsed laser deposition of epitaxial thin films of the magnetically frustrated FeV2O4 spinel vanadate compound. A precise optimization of the oxygen pressure deposition conditions was necessary to avoid the presence of volatile over-oxidated vanadium while avoiding the presence of oxygen vacancies. We report the effect of the epitaxial compressive stress induced by the MgO substrates on the structural and magnetic properties of the films. The surprising films lattice parameters reduction in all directions lead to an unusual auxetic behaviour. The reduced volume of the cell results in a decrease of the V–V distances. This allows a 50 K increase of the magnetic transition temperature, which now reaches 160 K. The epitaxial strain tuning of the magnetic order in the iron-based vanadates open new degrees of freedom towards the integration of the films in oxide electronics.