Valley-Related Multipiezo Effect and Noncollinear Spin Current in an Altermagnet FeSeO Monolayer.

An altermagnet exhibits many novel physical phenomena because of its intrinsic antiferromagnetic coupling and natural band spin splitting, which are expected to give rise to new types of magnetic electronic components. In this study, an FeSeO monolayer is proven to be an altermagnet with out-of-plane magnetic anisotropy, and its Néel temperature is determined to be 319 K. The spin splitting of the FeSeO monolayer reaches 860 meV. Moreover, an FeSeO monolayer presents a pair of energy valleys, which can be polarized and reversed by applying uniaxial strains along different directions, resulting in a piezovalley effect. Under the strain, the net magnetization can be induced in the FeSeO monolayer by doping with holes, thereby realizing a piezomagnetic property. Interestingly, noncollinear spin current can be generated by applying an in-plane electric field on an unstrained FeSeO monolayer doped with 0.2 hole/formula unit. These excellent physical properties make the FeSeO monolayer a promising candidate for multifunctional spintronic and valleytronic devices.