External Electric Field Driving the Ultra-low Thermal Conductivity of Silicene

Manipulation of thermal transport (pursuing ultra-high or ultra-low thermal conductivity) is on emerging demands, since heat transfer plays a critical role in enormous practical implications, such as efficient heat dissipation in nano-electronics and heat conduction hindering in solid-state thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure, which would be frustrated due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (k). Taking two-dimensional silicon (silicene) as a model system, we demonstrate that, by applying electric field (E_z = 0.5 V/Å) the thermal conductivity of silicene can be reduced to a record low value of ~0.091 W/mK. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure.