Oral: Switchable altermagnetism of two-dimensional polar-stacked bilayers

Recently, colinear antiferromagnets with non-relativistic spin splitting of their electronic band structure, now known as altermagnets, gained significant interest due to their potential applications in spintronics. While many intrinsic 3D altermagnets have been proposed theoretically and some of them realized experimentally, altermagnetism in 2D systems remained largely unexplored. In this work, we discuss the possibility of converting a conventional 2D antiferromagnet into an altermagnet by breaking symmetries that enforce spin degeneracy of electronic bands, while maintaining net magnetization zero. Specifically, we consider polar stacking of van der Waals bilayers which break inversion symmetry and induce out-of-plane electric polarization. Using density-functional calculations, we explore several polar-stacked antiferromagnetic van der Waals bilayer structures and show that they exhibit artificial altermagnetism with a sizable spin splitting of their electronic bands. Importantly, the spin-splitting in these artificial altermagnets can be reversed by electric polarization switching without disturbing the antiferromagnetic Néel vector. This new functionality is interesting for application in magnetic tunnel junctions and spin-filtering devices.