Anomalous thermal expansion of Sb$_2$Te$_3$ topological insulator

摘要

We have investigated the temperature dependence of the linear thermalexpansion along the hexagonal c axis ($\Delta L$), in-plane resistivity($\rho$), and specific heat ($C_p$) of the topological insulator Sb$_2$Te$_3$single crystal. $\Delta L$ exhibits a clear anomaly in the temperature region204-236 K. The coefficient of linear thermal expansion $\alpha$ decreasesrapidly above 204 K, passes through a deep minimum at around 225 K and thenincreases abruptly in the region 225-236 K. $\alpha$ is negative in theinterval 221-228 K. The temperature dependence of both $\alpha$ and $C_p$ canbe described well by the Debye model from 2 to 290 K, excluding the regionaround the anomaly in $\alpha$.