Superconductivity in the topological Insulator Bi 2 Se 3 (DMR 0819860)

1. Superconductivity in the topological Insulator Bi2Se3 (DMR 0819860) IRG-A : Y. S. Hor, A. J. Williams, J. G. Checkelsky, P. Roushan, J. Seo, Q. Xu, H.W. Zandbergen, A. Yazdani, N. P. Ong, and R. J. Cava In a conventional insulator, electrical conduction is prohibited by a large energy gap which separates the occupied electronic states from the unoccupied states. Scientists are actively investigating a novel class of insulators, called topological insulators, in which current can flow on the surface. Electrons on the surface display several unusual properties. For example, their spin can have only one polarization direction (spins in ordinary metals can have either polarization). Because the surface electrons remain conducting to very low temperatures, researchers have wondered if they can become superconducting. Researchers at PCCM have taken a big step in this direction (1,2). They showed that the topological insulator Bi2Se3, doped with Cu, becomes a superconductor when cooled below 4 Kelvin: electrons in Bi2Se3 readily form Cooper pairs – the hallmark of superconductivity. The finding brightens prospects for realizing a new class of electronic devices based on superconductivity induced in the topological surface states. Fig. 1 Copper induces Cooper pairing and superconductivity in the topological insulator Bi2Se3. 1. Y. S. Hor et al. Phys. Rev. Lett. 104, 057001 (2010). 2. N. Bray-Ali and S. Haas, Physics 3, 11 (2010), Viewpoint