Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Superconductivity: Fe-based Superconductors - FeSe and others
TT 59.3: Vortrag
Donnerstag, 23. März 2017, 10:00–10:15, HSZ 103
Nodeless superconductivity and impurity bound states in FeSe single crystals — •Sahana Roessler1, Lin Jiao1, Chien-Lung Huang1, Cevriye Koz1, Ulrich K. Roessler2, Ulrich Schwarz1, and Steffen Wirth1 — 1Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany — 2IFW-Dresden, Institute for Solid State Research, D-01171 Dresden, Germany
We present the superconducting gap structure of FeSe single crystals [1,2] investigated by heat capacity and scanning tunneling microscopy/spectroscopy (STM/S). We show evidence for the existence of two superconducting gaps without nodes [3]. Further, the local density of states in the vicinity of a native selenium dumbbell in the superconducting state displays two resonant states inside the superconducting gap, equally spaced with respect to zero energy, but asymmetric in amplitude. The magnitude of the superconducting gap is found to be insensitive to the impurity potential, which confirms its non-magnetic nature. The in-gap bound states emerging from a nonmagnetic impurity-induced pair-breaking suggest a sign changing pairing state in this material.
[1] C. Koz et al., Z. Anorg. Allg. Chem. 640, 1600 (2014)
[2] S. Rößler et al., PRB(R) 92, 060505 (2015)
[3] L. Jiao et al., arXiv:1605.01908 (2016)