The effect of magnetic order on the thermal transport properties of the intrinsic two-dimensional magnet 2H-VSe.

By using first-principles calculations combined with the phonon Boltzmann transport equation, in this work, we systematically investigate the effect of magnetic order on the phonon and thermal transport properties of the intrinsic two dimensional magnet 2H-VSe. The results show that 2H-VSe is dynamically stable in both paramagnetic and ferromagnetic phases, and the obvious discrepancy of characteristic frequencies of Raman-active phonon modes provides a reliable way to identify the magnetic phase. Meanwhile, our calculations also indicate that the magnetic order has a vital effect on the thermal transport properties. Around the Curie temperature (500 K), the thermal conductivity of 2H-VSe in the FM phase (16.3 W mK) is about four times larger than that in the PM phase (4.3 W mK), and such a difference could be maintained even when considering the temperature dependent force constants. By analyzing the phonon mode information and root mean square displacement, we reveal that large atomic interactions and suppressed phonon anharmonicity are the main roots for the enhanced thermal conductivity in the FM phase 2H-VSe. These results further demonstrate that magnetic materials with a FM phase always host more excellent thermal transport properties than those with a PM phase, and shed light on the great potential applications of thermal switching devices based on 2H-VSe.