Anomalous Thermal Hall Effect in an Insulating van der Waals Magnet

Two-dimensional (2D) van der Waals (vdW) magnets have been a fertile playground for the discovery and exploration of physical phenomena and new physics. In this Letter, we report the observation of an anomalous thermal Hall effect (THE) with kappa(xy) similar to 1 x 10(-2) WK-1 m(-1) in an insulating van der Waals ferromagnet VI3. The thermal Hall signal persists in the absence of an external magnetic field and flips sign upon the switching of the magnetization. In combination with theoretical calculations, we show that VI3 exhibits a dual nature of the THE, i.e., dominated by topological magnons hosted by the ferromagnetic honeycomb lattice at higher temperatures and by phonons induced by the magnon-phonon coupling at lower temperatures. Our results not only position VI3 as the first ferromagnetic system to investigate both anomalous magnon and phonon THEs, but also render it as a potential platform for spintronics-magnonics applications.

Automated summary

The study reports the observation of an anomalous thermal Hall effect in the insulating van der Waals ferromagnet VI3, indicating a dual nature of the effect dominated by topological magnons and phonons. These results position VI3 as a potential platform for spintronics-magnonics applications.