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TT: Fachverband Tiefe Temperaturen

TT 35: Superconductivity: Fe-based Superconductors - 122 and Theory

TT 35.4: Vortrag

Dienstag, 13. März 2018, 10:15–10:30, A 053

Superconductivity with broken time reversal symmetry in Ba_1−xK_xFe₂As₂ single crystals — •Vadim Grinenko^1,2, Philipp Materne¹, Rajib Sarkar¹, Sirko Kamusella¹, Kunihiro Kihou³, Chul-Ho Lee³, Shavkat Akhmadaliev⁴, Dmitriy Efremov², Stefan-Ludwig Drechsler², Hubertus Luetkens⁵, and Hans-Henning Klauss¹ — ¹Institute for Solid State and Material Physics, TU Dresden, 01069 Dresden, Germany — ²IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany — ³National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8560 Japan — ⁴Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany — ⁵Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland

Over the last years a lot of theoretical and experimental efforts have been made to find states with broken time reversal symmetry (BTRS) in multi-band superconductors below the superconducting transition temperature (T_c). In particular, it was theoretically proposed that in the Ba_1−xK_xFe₂As₂ system either an s+is or an s+id BTRS state may exist at high doping levels in a narrow region of the phase diagram. Here we report the observation of an enhanced zero field muon spin relaxation rate at T^* T_c for a high quality crystalline samples in the doping range 0.8 x 0.7. We found that T^* is strongly doping dependent. Our results are consistent with the multi-band s+is superconducting state in Ba_1−xK_xFe₂As₂ in this doping range.