All-electrical switching of spin texture in a strain-tunable 2D Janus ferroelectric altermagnet

TL;DR

This study predicts a 2D Janus VOClBr material with coupled ferroelectric and altermagnetic properties, enabling electric control of spin textures and potential for multifunctional spintronic devices, based on first-principles calculations.

Contribution

It identifies a strain-tunable 2D ferroelectric altermagnet with strong magnetoelectric coupling, enabling all-electrical control of spin textures in a single material.

Findings

Complete reversal of spin polarization upon ferroelectric switching.

Strain significantly reduces the ferroelectric switching barrier.

Strain induces a phase transition to an antiferromagnetic state.

Abstract

Altermagnetism (AM), a collinear magnetic phase with momentum-dependent spin splitting, is a promising candidate for strong magnetoelectric coupling. However, realizing direct and tunable coupling between ferroelectricity (FE) and AM within a single two-dimensional (2D) material remains an outstanding challenge. Here, based on first-principles calculations, we identify the distorted phase of monolayer Janus VOClBr as an intrinsic 2D FE-AM. This phase demonstrates robust magnetoelectric coupling, as evidenced by a complete reversal of momentum-space spin polarization upon FE switching, and further supported by spin texture analysis and the magneto-optical Kerr effect. Notably, the FE properties are highly strain-tunable: biaxial compression strain of -4% reduces the FE polarization switching barrier by approximately 87%, whereas a tensile strain of +3% induces a phase transition to an antiferromagnet. Leveraging the lock-in between the electrically controlled spin texture and the magneto-optical Kerr effect signal, we propose a non-volatile, polymorphic spintronic memory device featuring all-electrical writing and optical readout. This work establishes 2D FE-AMs as a versatile platform for coupled ferroic orders and paves the way for voltage-controlled, multifunctional spin-logic devices.