Speaker
Description
Altermagnets are a novel type of magnetic system that has a spin-polarized electric band structure in the absence of a net magnetic moment. Microscopically this arises from two opposite spin sublattices that are connected by a lattice rotational symmetry instead of a simple translation or inversion [1]. A ferromagnetic-like transport response makes these systems particularly interesting for potential device applications [2]. Hexagonal MnTe is a prototypical altermagnet consisting of alternating ferromagnetically ordered Mn layers [3,4]. Importantly, it exhibits the expected strong spin splittings in the electronic band structure [5]. Here we present muon spin spectroscopy ($\mu$SR) measurements on MnTe single crystals and thin films. Surprisingly, below room temperature we observe pronounced anomalies in the depolarization as well as an onset of a second, non-proportionate zero field oscillation frequency. These findings point to a more complex temperature evolution of the local magnetic environment probed by the muon.
Figure: Depolarization rate and local field measured in zero field $\mu$SR. The inset shows the expected altermagnetic structure.
[1] L. Šmejkal et al., Sci Adv. 6, eaaz8809 (2020)
[2] L. Bai et al., Adv. Funct. Mater. 2024, 2409327 (2024)
[3] N. Kunitomi, et al., J. Physique 25, 568 (1964)
[4] D. Kriegner, et al., PRB 96, 214418 (2017)
[5] J. Krempaský, et al., Nature 626, 517–522 (2024)
| jonas.krieger@psi.ch | |
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