NMR probe of suppressed bulk conductivity in the topological insulator BiSbTe.

The relaxation behavior in the topological insulator (TI) BiSbTe has been investigated using Te nuclear magnetic resonance spectroscopy. We systematically investigate the spin-lattice relaxation rate (1/ ) in bulk electronic states with varying particle sizes. By analyzing the 1/ relaxation behavior, we find that with decreasing particle sizes the electronic states in the bulk exhibit more topological insulating behavior, indicative of an increasing energy gap supported by higher thermal activation energy.