Unusual Thermal Transport in Few-Layer Van der Waals Antiferromagnet CrOCl.

Few-layer van der Waals magnets are exceptional candidates for investigating the fundamental spin behaviors and advancing the development of next-generation ultra-compact spintronic devices. While the intrinsic long-range magnetic order is well-established in the monolayer limit, the thermal transport behavior involving magnons, phonons, and magnetophonon polarons near the phase transition remains largely unexplored. In this work, the thermal transport behavior is probed near the phase transitions from bulk to the monolayer limit by using a differential suspended thermal bridge method, which provides an ultra-sensitive temperature and thermal conductance measurement enhanced by the double Wheatstone bridge. In the few-layer CrOCl flake, a stronger magnon-phonon coupling is observed compared to the bulk, resulting in a shift in the thermal transport behavior from a dip to a peak shape around the Néel temperature. Additionally, below the Néel temperature, the few-layer CrOCl significantly enhances the interfacial thermal conductance between the metal electrode and insulator substrate, potentially leading to the substantial improvements in the heat dissipation in Si-based semiconductor devices. This study introduces a novel method and strategy for probing the fundamental magnetic phase transition behavior and lays a solid foundation for the potential application of van der Waals magnets in the electronic devices.