Characterization of Altermagnetic MnTe Films Grown by Molecular Beam Epitaxy on Al₂O₃ (0001) Substrates

Altermagnetism is a newly-identified spin-symmetry classification of collinear magnets which is distinct from ferromagnetism and antiferromagnetism [1]. Altermagnets are a compensated magnetic phase with vanishing net magnetization – similar to antiferromagnets – but which also exhibit non-relativistic lifting of Kramers spin degeneracy and spin-polarized bands – similar to ferromagnets, which can be utilized in the development of next-generation spin-based technologies such as spintronics. The development of high-quality thin film altermagnet materials is therefore crucial for the advancement of fundamental understanding of this new class of materials as well as practical device applications.

MnTe with the hexagonal NiAs-type structure (α-MnTe) is predicted to be an altermagnet with a relatively large spin-splitting of ~1 eV and a relatively high critical temperature of 310 K [1,2]. Here we present the growth of high-quality α-MnTe films by molecular beam epitaxy on a robust and widely available substrate, Al₂O₃ (0001). We find that growth on novel buffer layers significantly improves the growth morphology, as evidenced by smooth surfaces revealed by atomic force microscopy. X-ray diffraction confirms the growth of single-phase, c axis-oriented films. SQUID magnetometry and transport results will also be presented, as well as preliminary spin-resolved ARPES measurements.

[1] Šmejkal, L., et al. Phys. Rev. X 12, 031042 (2022).

[2] Mazin, I. I. Phys. Rev. B 107, L100418 (2023).