Direct magnetization-polarization coupling in BaCuF$_4$ fluoride

TL;DR

This paper reports from first-principles calculations that BaCuF4 exhibits ideal magnetization reversal via polarization switching near room temperature, driven by a soft mode linking polarization and octahedral rotation, making it promising for multifunctional devices.

Contribution

It introduces BaCuF4 as a new prototype with ideal magnetization-polarization coupling driven by a soft mode, suitable for room-temperature applications.

Findings

Magnetization reversal can be achieved through polarization switching.

Coupling is driven by a soft mode involving polarization and octahedral rotation.

BaCuF4 shows potential for multifunctional device applications.

Abstract

Despite oxides and some fluorides perovskites have emerged as prototypes of multiferroic and magnetoelectric materials, they have not impacted real devices. Unfortunately, their working temperatures are very low and the magnetoelectric coupling has been reported to be rather small. Herewith, we report from first-principles calculations an ideal magnetization reversal through polarization switching in BaCuF$_4$ which, according to our results, could be achieved close to room temperature. We also show that this ideal coupling is driven by a soft mode that combines both, polarization and octahedral rotation. The later being directly coupled to the weak ferromagnetism of BaCuF$_4$. This, added to its strong Jahn-Teller distortion and its orbital ordering, makes this material as a very appealing prototype for crystals in the $ABX_4$ family in multifunctional applications.