Multiple Zeeman-type hidden spin splittings in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="script">PT</mml:mi></mml:math>-symmetric layered antiferromagnets

Abstract

Centrosymmetric antiferromagnetic semiconductors, although abundant in nature, appear less favorable in spintronics owing to the lack of inherent spin polarization and magnetization. We unveil hidden Zeeman-type spin splitting in layered centrosymmetric antiferromagnets with asymmetric sublayer structures through first-principles simulations and symmetry analysis. Taking the bilayer counterpart of recently synthesized monolayer MnSe, we demonstrate that the degenerate states around specific $\mathbit{k}$ points spatially segregate on different sublayers forming $\mathcal{PT}$-symmetric pairs. Furthermore, degenerate states exhibit uniform in-plane spin configurations with opposite orientations enforced by mirror symmetry. Bands are locally Zeeman split up to order of $\ensuremath{\sim}70\phantom{\rule{4pt}{0ex}}\mathrm{meV}$. Strikingly, a tiny electric field of a few $\mathrm{mV}{\AA{}}^{\ensuremath{-}1}$ along the $z$ direction breaks the double degeneracy forming additional Zeeman pairs. The design principle to obtain Zeeman-type splitting in centrosymmetric antiferromagnets established here expands the range of materials among which to look for spintronics.