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TT: Fachverband Tiefe Temperaturen

TT 108: Topological Superconductors

TT 108.4: Vortrag

Freitag, 16. März 2018, 10:15–10:30, H 2053

Nematic superconductivity in Cu_xBi₂Se₃ — •Matthias Hecker and Jörg Schmalian — KIT, Karlsruhe, Germany

Cu_xBi₂Se₃ is a doped topological insulator that becomes superconducting at a temperature T_c ≈ 3.8 K. Recent NMR Knight-shift measurements in the superconducting phase have revealed the spontaneous symmetry breaking of the threefold rotational symmetry of the underlying lattice, in addition to the global U(1)-symmetry. This fact is most consistent with an odd-parity two-component superconducting order parameter, as proposed by [1]. We study the role of order parameter fluctuations, and show that the system can realize a nematic phase with T_nem> T_c, where actual superconductivity is not yet present. Besides, we find that the nematic phase transition is always a first order transition. Inside this new phase, we calculate the anisotropy in the resistivity in order to provide a tool for experimental verification.
Fu and Berg, PRL 105,4 097001 (2010)