Unveiling magnetic transition-driven lattice thermal conductivity switching in 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 phonon-mediated thermal properties of H-phase monolayer VS₂, a two-dimensional (2D) 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 the stiffening of the V–S bonds, thereby modifying the frequencies of different vibrational modes. Phonon–phonon interaction 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 53.98 W m⁻¹ K⁻¹ in the ferromagnetic phase to 12.10 W m⁻¹ K⁻¹ in the paramagnetic phase. By elucidating heat transport in two-dimensional ferromagnets, our study offers valuable insights for manipulating and converting thermal energy.