Robust magnetoelectric coupling in altermagnetic-ferroelectric type-III multiferroics

TL;DR

This paper introduces a new class of multiferroics where ferroelectricity and altermagnetism are intrinsically linked through crystal symmetry, enabling robust magnetoelectric coupling suitable for advanced spintronic applications.

Contribution

It proposes a novel type-III multiferroic class with inherent coupling between ferroelectricity and altermagnetism, supported by first-principles calculations and magneto-optical Kerr effect analysis.

Findings

Ferroelectric switching in these materials fully inverts altermagnetic spin polarization.

Strong magnetoelectric coupling demonstrated through magneto-optical Kerr effect.

Theoretical foundation for designing next-generation spintronic devices.

Abstract

Multiferroic materials, characterized by the coexisting of ferroelectric polarization (breaking spatial inversion symmetry) and magnetism (breaking time-reversal symmetry), with strong magnetoelectric coupling, are highly sought after for advanced technological applications. Novel altermagnets, distinct from conventional magnets, have recently been revealed to exhibit unique spin polarization protected by crystal symmetry, which naturally overcomes the isolation of magnetism from ferroelectrics associated with spatial symmetry. In this study, we propose a novel class of type-III multiferroics, where ferroelectricity and altermagnetism are inherently interlocked by crystal symmetry, setting them apart from conventional multiferroics. Through first-principles calculations, ferroelectric switching is shown to fully invert the spin polarization of altermagnets, equivalent to a 180{\deg} reversal of magnetic spin. This strong magnetoelectric coupling is further supported by the magneto-optical Kerr effect, revealing a new class of multiferroics with robust, symmetry-driven magnetoelectric coupling and providing a theoretical foundation for the design of next-generation spintronic devices leveraging altermagnetism.