Thermal Hall effects due to topological spin fluctuations in YMnO$_3$

• DOI: 10.48550/arxiv.2311.11527
• Publication Date: 2023-01-01
• Authors: Ha-Leem Kim; Takuma Saito; Heejun Yang; Hiroaki Ishizuka; Matthew J. Coak; Jun Han Lee; Hasung Sim; Yoon Seok Oh; Naoto Nagaosa; Je-Geun Park
• Keywords: Thermal Hall effect; Magnon; Hexagonal Lattice; Thermal fluctuations

The thermal Hall effect in magnetic insulators has been considered a powerful method for examining the topological nature of charge-neutral quasiparticles such as magnons. Yet, unlike kagome system, triangular lattice received less attention studying because scalar spin chirality cancels out between adjacent triangles. However, cancellation cannot be perfect if is distorted, which could open possibility non-zero effect. Here, we report that trimerized multiferroic hexagonal manganite YMnO$_3$ produces highly unusual due to fluctuations with additional intricacy Dzyaloshinskii-Moriya interaction under an applied field. We conclude conductivity arises from system's fluctuations. Our theoretical calculations demonstrate also related this material splitting otherwise degenerate two chiralities, left and right, its 120$^{\circ}$ structure. result one most cases physics broken $Z_2$ symmetry supposedly paramagnetic state YMnO$_3$, strong These new mechanisms important class materials are crucial exploring exotic excitations.