Wednesday, July 3, 2013

1307.0260 (L. Fang et al.)

Quantized Interface Topological State and Superconductivity in the
Homologous Structures (AgxPb1-xSe)5(Bi2Se3)3m, m=1,2

L. Fang, C. C. Stoumpos, Y. Jia, A. Glatz, D. Y. Chung, H. Claus, U. Welp, W. K. Kwok, M. G. Kanatzidis
Quantum diffusion of topological surface states are generally overshadowed by the transport of bulk Schr\"odinger electrons. Material engineering such as chemical doping and sample size reduction can enable effective mitigation of the bulk contribution. In this article, we report on a new approach to significantly magnify the topological state using naturally formed heterostructure of homology (Ag1-xPbxSe)5(Bi2Se3)3m, m=1, 2, where the Bi2Se3 layers periodically separated by insulating Ag1-xPbxSe layers. Two-dimensional weak antilocalization (WAL) effect, one of the hallmarks of the topological state, was observed in m=2 (Ag1-xPbxSe)5(Bi2Se3)6 phase. Quantitative analysis of the WAL state reveals that the quantum correction to the conductivity is equal to the conductance quantum, e2/2{\pi}h, multiplied by the number of Bi2Se3 quintuple layers. The m=1 (Ag1-xPbxSe)5(Bi2Se3)3 phase is a new superconductor with a Tc ~ 1.7 K. The homologous structure allows intergrowth of the superconducting m=1 phase and the topological m=2 phase to occur naturally. We thus propose that the opportunity to observe the Majorana Fermion state may lie at the boundary of two inter-grown crystals.
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