Altermagnetism of ultrathin CrSb slabs

Altermagnets exhibit momentum-dependent spin splitting without net magnetization, combining characteristics of both ferromagnets and antiferromagnets, making them highly interesting for spintronics applications. CrSb is a prime candidate with a high Néel temperature ($\sim 700$~K) and a large exchange-driven splitting of $\sim 0.6$–1~eV. Using ab-initio calculations, we consider slabs of various orientations in the ultrathin limit. We find that (100) oriented slabs have spin-degenerate bands. In (0001) oriented slabs, the exchange-driven altermagnetic spin splitting collapses, but including spin-orbit coupling restores a residual anisotropic splitting of $\sim 70$~meV. In contrast, the (110) oriented slabs show an altermagnetic spin splitting of $\sim 400$~meV, and emerges as a robust candidate for realizing large, exchange-driven altermagnetism