Evidence for Time-Reversal-Symmetry-Broken Superconductivity in Locally Noncentrosymmetric SrPtAs

P. K. Biswas; H. Luetkens; T. Neupert; T. Stuerzer; C. Baines; G. Pascua; A. P. Schnyder; M. H. Fischer; J. Goryo; M. R. Lees; H. Maeter; F. Brueckner; H. -H. Klauss; M. Nicklas; P. J. Baker; A. D. Hillier; M. Sigrist; A. Amato; D. Johrendt

doi:10.1103/physrevb.87.180503

arXiv · 1212.2441

Evidence for Time-Reversal-Symmetry-Broken Superconductivity in Locally Noncentrosymmetric SrPtAs

P. K. Biswas·H. Luetkens·T. Neupert·T. Stuerzer·C. Baines·G. Pascua·A. P. Schnyder·M. H. Fischer·J. Goryo·M. R. Lees·H. Maeter·F. Brueckner·H. -H. Klauss·M. Nicklas·P. J. Baker·A. D. Hillier·M. Sigrist·A. Amato·D. Johrendt

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Abstract

We report the magnetic and superconducting properties of locally noncentrosymmetric SrPtAs obtained by muon-spin-rotation/relaxation (muSR) measurements. Zero-field muSR reveals the occurrence of small spontaneous static magnetic fields with the onset of superconductivity. This finding suggests that the superconducting state of SrPtAs breaks time-reversal symmetry. The superfluid density as determined by transverse field muSR is nearly flat approaching T = 0 K proving the absence of extended nodes in the gap function. By symmetry, several superconducting states supporting time-reversal symmetry breaking in SrPtAs are allowed. Out of these, a dominantly d + id (chiral d-wave) order parameter is most consistent with our experimental data.

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P. K. Biswas, H. Luetkens, T. Neupert, T. Stuerzer, C. Baines, G. Pascua, A. P. Schnyder, M. H. Fischer, J. Goryo, M. R. Lees, H. Maeter, F. Brueckner, H. -H. Klauss, M. Nicklas, P. J. Baker, A. D. Hillier, M. Sigrist, A. Amato, D. Johrendt. 2013-03-21. Evidence for Time-Reversal-Symmetry-Broken Superconductivity in Locally Noncentrosymmetric SrPtAs. https://doi.org/10.1103/physrevb.87.180503

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