Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 20: Cryotechnique & Measuring Devices: Poster Session

TT 20.4: Poster

Montag, 7. März 2016, 15:00–18:00, Poster D

Experimental aspects of the specific heat of superconductors derived from topological insulators — •Lionel Andersen, Oliver Breunig, Thomas Lorenz, and Yoichi Ando — II. Physikalisches Institut - Universität zu Köln, Germany

The expectation for topological superconductors to have an unconventional pairing symmetry makes them promising hosts for Majorana fermions. Recently the topological insulators Bi₂Se₃ (BS) and (PbSe)₅(Bi₂Se₃)₆ (PSBS) were reported to become superconducting when intercalating them with copper [1, 2]. Literature data of specific heat on both, Cu_xBS and Cu_xPSBS, indicate an unusual temperature dependence not described by standard BCS theory [2, 3]. This makes them promising candidates of topological superconductors but in order to clarify these issues it is necessary to perform c_p measurements below 250 mK using a ³He/⁴He dilution cryostat. Because c_p of superconductors becomes very small far below T_c the addendum contribution of the setup has to be minimized. This demand together with other complications e.g. nuclear Schottky contributions to c_p, leads to a drastic increase of the experimental effort. In this contribution experimental aspects of c_p measurements with respect to the topological superconductor materials will be discussed in detail.
[1] Y. S. Hor et al., PRL 104 057001 (2010)
[2] Y. Ando et al., PRB 90 220504 (2014)
[3] Y. Ando et al., PRL 106 127004 (2011)