Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 28: Topological Insulators (joint session MA/KFM)

KFM 28.8: Vortrag

Donnerstag, 8. September 2022, 17:00–17:15, H37

Thermal Hall Effect of Magnons in Collinear Antiferromagnets: Signatures of Magnetic and Topological Phase Transitions — •Robin R. Neumann¹, Alexander Mook², Jürgen Henk¹, and Ingrid Mertig¹ — ¹Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany — ²Department of Physics, University of Basel, Basel, Switzerland

While chiral edge states of topological bosons lack clear hallmarks and are difficult to detect, topological electrons can directly be identified by means of the quantized transverse conductivity intrinsic to the quantum anomalous Hall effect. In this talk I consider magnons, the bosonic quanta of collective spin excitations, in a collinear antiferromagnet that is driven from its antiferromagnetic phase via a spin-flop phase to the field-polarized phase by an external magnetic field. Besides the magnetic phase transitions, topological phases occur in the spin-flop and field-polarized phases. To identify these phase transitions, the thermal Hall effect (THE), i. e. the transversal heat transport induced by a longitudinal temperature gradient, is studied across the phase transitions. It is demonstrated that the THE exhibits pronounced signatures of the phase transitions and the temperature tunes the sensitivity to these phase transitions oppositely, allowing for their distinction in transport experiments.