Ferroelectricity-driven altermagnetism in two-dimensional van der Waals multiferroics

TL;DR

This paper demonstrates how ferroelectric polarization and interlayer sliding can control altermagnetism in 2D van der Waals multiferroics, enabling electrically tunable spin splitting and anomalous Hall effects for spintronic applications.

Contribution

It introduces a novel strategy to manipulate altermagnetism in 2D multiferroics using symmetry analysis and first-principles calculations, highlighting material candidates like FeCuP2S6.

Findings

Monolayer and bilayer FeCuP2S6 exhibit spin splitting due to nonsymmorphic symmetries.

Interlayer sliding enables reversible control of spin splitting.

Anomalous Hall response directly probes the spin-split states.

Abstract

Altermagnets (AMs) are a recently identified class of unconventional collinear compensated antiferromagnets that exhibit momentum-dependent spin splitting despite having zero net magnetization. This unconventional magnetic order gives rise to a range of phenomena, including the anomalous Hall effect, chiral magnons, and nonlinear photocurrents. Here, using spin space group (SSG) symmetry analysis and first-principles calculations, we demonstrate an efficient strategy to control altermagnetism in two-dimensional multiferroics through ferroelectric polarization and interlayer sliding. For material realization, we find that monolayer and bilayer FeCuP2S6 exhibit finite spin splitting when ferroelectric sublattices are connected by nonsymmorphic screw-axis operations rather than pure translation or inversion symmetry. Interlayer sliding further enables reversible switching or suppression of spin splitting through modifications of the SSG. Our calculations further reveal that the anomalous Hall response serves as a direct probe of these spin-split states. These findings establish two-dimensional van der Waals multiferroics as promising platforms for realizing electrically controllable altermagnetism and advancing next-generation spintronic and magnetoelectric technologies.