Topological-Metal to Band-Insulator Transition in (Bi1-xInx)2Se3 Thin Films

By combining transport and photo emission measurements on (Bi1-xInx)2Se3 thin films, we report that this system transforms from a topologically non-trivial metal into a topologically trivial band insulator through three quantum phase transitions. At x = 3-7%, there is a transition from a topologically non-trivial metal to a trivial metal. At x = 15%, the metal becomes a variable-range-hopping insulator. Finally, above x = 25%, the system becomes a true band insulator with its resistance immeasurably large even at room temperature. This material provides a new venue to investigate topologically tunable physics and devices with seamless gating/tunneling insulators.