Altermagnetic band splitting in 10 nm epitaxial CrSb thin films

Altermagnets are magnetic materials with a unique antiferromagnetic real space ordering, and a momentum dependent spin polarized electronic band structure. Among the attractive altermagnets with large spin-splitting near the Fermi level, CrSb is special due to a high Néel transition temperature of around 700 K. We use molecular beam epitaxy to synthesize CrSb (0001) thin films with thickness ranging from 10 nm to 100 nm. Structural characterization demonstrates the growth of epitaxial films with good crystallinity. Polarized neutron reflectometry proves the absence of any net magnetization, consistent with antiferromagnetic order. In vacuo angle resolved photoemission spectroscopy (ARPES) measurements show a bulk-type, three-dimensional momentum dependent band splitting of up to 0.7 eV with g-wave symmetry in a previously unexplored film thickness of 10 nm. Our results are consistent with prior studies of bulk single crystals and bulk-like thin films. In our study, we show that the distinct altermagnetic band structure in CrSb required for potential magnetism and spin-transport applications survives down to the ∼ 10 nm thin film limit at room temperature.