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MA: Fachverband Magnetismus

MA 52: Altermagnets

MA 52.15: Vortrag

Freitag, 22. März 2024, 13:15–13:30, EB 202

Zero-Field Crystal Thermal Hall Effect in Insulating Altermagnets — •Rhea Hoyer, Libor Šmejkal, and Alexander Mook — Johannes Gutenberg Universität Mainz, Mainz, Deutschland

The thermal Hall effect is an emerging probe of charge-neutral collective excitations in insulating quantum matter. Here we address the question of whether thermal Hall effects can occur in compensated collinear magnets at zero magnetic field. Following the recently developed concept of altermagnetism [1,2,3], we provide an affirmative answer by developing a minimal model that exhibits a crystal thermal Hall effect. Specifically, we present a Heisenberg-type spin model on the rutile lattice. The presence of nonmagnetic atoms causes altermagnetic spin-splitting of magnons [4,5] and gives rise to Dzyaloshinskii-Moriya interaction. As microscopic heat carriers, we consider magnons, whose Berry curvature causes an intrinsic contribution to the thermal Hall conductivity [6]. We show how the Hall conductivity changes as a function of the Néel vector direction, highlighting the influence of magnetic point group symmetries. The role of symmetry is further emphasized by studying fluctuation induced piezomagnetism and strain engineering of the Hall conductivity. Finally, the thermal Hall response is contrasted with a spin-Nernst response to explore the potential for heat-to-spin conversion in altermagnetic insulators.

[1] L.Š. et al., PRX 12, 031042 (2022). [2] L.Š. et al., PRX 12, 040501 (2022). [3] L.Š. et al., Sci. Adv.6, eaaz8809 (2020). [4] L.Š. et al., arXiv:2211.13806 (PRL, accepted). [5] M.G. et al., PRL 126, 127701 (2023). [6] R.M. et al., PRL 106, 197202 (2011).

Keywords: Thermal Hall Effect; Magnons; Altermagnetism