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

By combining transport and photoemission measurements on (Bi1-xInx)(2)Se-3 thin films, we report that this system transforms from a topologically nontrivial metal into a topologically trivial band insulator through three quantum phase transitions. At x approximate to 3%-7%, there is a transition from a topologically nontrivial metal to a trivial metal. At x approximate to 15%, the metal becomes a variable-range-hopping insulator. Finally, above x approximate to 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 or tunneling insulators.