Unveiling Magnetic Transition-Driven Thermal Conductivity Switching in Semiconducting Monolayer VS2

Abstract

Effective thermal management is essential for maintaining the operational stability and data security of magnetic devices across diverse fields, including thermoelectric, sensing, data storage, and spintronics. In this study, density functional theory calculations were conducted to explore the spin-induced modifications in the thermal properties of the H-phase monolayer VS₂, a two-dimensional (2D) semiconducting ferromagnet. Our investigation revealed that the 2D H-phase of VS2 exhibits a substantial thermal switching ratio, exceeding four at the Curie temperature, due to the coupling between magnetic order and lattice vibrations. This sensitivity arises from spin-dependent lattice anharmonicity, which results in a stiffening of the V-S bonds, thereby modifying the frequencies of different vibrational modes. Phonon-phonon interactions calculations indicated that phonon-magnon scattering was more predominant in the paramagnetic (PM) phase than in the ferromagnetic (FM) phase, which resulted in a reduced phonon lifetime, mean free path and group velocity. As a result, the lattice thermal conductivity was calculated to drop from 15.18 W/m/K in the ferromagnetic phase to 3.59 W/m/K in the paramagnetic phase. By elucidating heat transport in two-dimensional ferromagnets, our study offers valuable insights for manipulating and converting thermal energy.