Room Temperature Thermal Switching Based on Monolayer Boron Nitride

The research on materials capable of manipulating thermal conductivity continues to fuel the development of thermal controlling devices. Here, using ab initio calculations and the Boltzmann transport equation, we demonstrate that the thermal conductivity of semi-fluorinated hexagonal boron nitride (h-BN) can be reversibly manipulated at 300 K, and the ratio for the regulation of thermal conductivity reaches up to 11.23. Such behavior originates from the high sensitivity of thermal conductivity to magnetic ordering. Semi-fluorinated h-BN is a paramagnetic material at room temperature due to its Curie temperature of 270 K. Impressively, semi-fluorinated h-BN can be modulated into a ferromagnetic system by adding an external magnetic field of 11.15 T, resulting in greatly and reversibly tunable thermal conductivity at room temperature. Furthermore, in-depth analyses of phonon properties show that compared with the paramagnetic phase, both ferromagnetic and antiferromagnetic semi-fluorinated h-BN significantly reduce phonon scattering and anharmonicity, thereby enhancing thermal conductivity. The results qualify semi-fluorinated h-BN as a potential candidate for thermal switching applications at room temperature.