Topological insulator phases in polycrystalline Bi2Te3 thin films

Polycrystalline thin films of Bi2Te3, a well-known topological insulator (TI), grown by RF sputtering shows metallic-like transport for a wide range of temperatures, T = 50 K to T = 225 K. For T > 225 K, the sample shows activated transport.. The metallic-like behavior at low temperatures can be understood within a model of overlapping surface states of the TI nanocrystallites in the film, suggesting that TI thin films of polycrystalline nature may also stabilize topologically protected states.