Symmetry-Driven Unconventional Magnetoelectric Coupling in Perovskite Altermagnets: From Bulk to the Two-Dimensional Limit

TL;DR

This paper explores how symmetry-driven magnetoelectric coupling in perovskite altermagnets persists from bulk to two-dimensional layers, revealing constraints and strategies to enhance their applicability in miniaturized spintronic devices.

Contribution

It systematically analyzes the dimensional evolution of ferroelectricity and magnetism in perovskite altermagnets, identifying conditions for their stability and proposing methods to extend their functional range.

Findings

Altermagnetism persists in 2D only with C-type antiferromagnetic order.

Symmetry-restricted multimode couplings govern ferroelectric polarization and spin splitting.

Strategies are proposed to overcome magnetic-configuration constraints.

Abstract

The emergence of altermagnets establishes a new paradigm for multiferroics. Unlike conventional multiferroics relying on direct magnetoelectric coupling, multiferroic altermagnets host a crystal-symmetry-mediated magnetoelectric interaction that is intrinsically more efficient and robust. Among candidate material platforms, layered perovskites are particularly appealing owing to their structural diversity and synthetic versatility. However, magnetoelectric properties at the two-dimensional scale remain largely unexplored, hindering their applicability in miniaturized, highly integrated devices. Here, we systematically investigate the dimensional evolution of ferroelectric polarization and magnetism in perovskite systems through symmetry analysis. We demonstrate that altermagnetism can persist in the two-dimensional limit, yet is strongly constrained by the magnetic configuration-with only C-type antiferromagnetic order supporting it. Based on mode-decomposition calculations, we further reveal that symmetry-restricted multimode couplings simultaneously govern ferroelectric polarization and altermagnetic spin splitting. Finally, combined with first-principles calculations, we propose several strategies to lift the magnetic-configuration constraint, extending the range of viable altermagnetic systems. These results underscore the critical role of dimensionality in symmetry-driven magnetoelectric coupling in perovskite altermagnets and pave the way toward next-generation electrically controlled spintronic and multiferroic devices.