Thermal Hall effect in insulating van der Waals magnets

Speaker: Xianglin Ke, Department of Physics and Astronomy, Michigan State University, USA Abstract: Thermal transport is also an important technique for studying low-energy excitations of quantum materials. Specifically, there has been considerable interest in using thermal transport measurements on insulating solids to probe their charge-neutral quasi-particles, i.e., magnons and phonons. In this talk, we will present our recent thermal transport studies on insulating van der Waals (vdW) magnets, focusing on ferromagnetic VI3. We show that this material exhibits an anomalous thermal Hall effect with large thermal Hall signal over a wide temperature region. The thermal Hall signal persists in the absence of an external magnetic field and flips sign upon the switching of the magnetization. The observed thermal Hall effect is of dual nature, dominated by topological magnons hosted by the ferromagnetic honeycomb lattice at higher temperatures while being driven by magnon polarons via magnon-phonon coupling at lower temperatures. If time permits, we will also present some new thermal transport studies on other 2D vdW magnets [2]. References [1] H. Zhang et al., Physical Review Letters 127, 247202 (2021). [2] C.Q. Xu et al, Physical Review B 107, L060404 (2023).