Lattice thermal conductivity switching via structural phase transition in ferromagnetic VI3

Abstract

The realization of reversible thermal conductivity through ferromagnetic ordering can improve the heat management and energy efficiency in magnetic materials-based devices. VI3, as a new layered ferromagnetic semiconductor, exhibits a structural phase transition from monoclinic (C2/m) to rhombohedral () phase as temperature decreases, making it a suitable platform to investigate thermal switching in magnetic phase transition materials. This work reveals that the thermal switching ratio of VI3 can reach 3.9 along the a-axis. Mechanical properties analysis indicates that the C2/m structure is stiffer than the one, causing the larger phonon velocity in C2/m phase. Moreover, due to the fewer phonon branches in C2/m phase, the number of phonon--phonon scattering channels in C2/m phase is smaller compared to that of phase. Both the larger phonon velocity and the longer phonon lifetime lead to larger lattice thermal conductivity in C2/m phase. This study uncovers the mechanical and thermal properties of VI3, which provides useful guides for designing magnetic materials-based devices such as thermal switch.