along with the application of uniaxial stress and disorder*

After extensive research, idea regarding the symmetry of the superconducting order parameter of Sr₂RuO₄ is still lacking a consensus. Recently, NMR experiments have ruled out the well-discussed p_x ± ip_y state [1]. Nevertheless, complex two-component order parameters are conventionally indicated by time-reversal-symmetry breaking (TRSB) superconductivity. In order to lift the degeneracy between such components application of uniaxial stress is a plausible method [2]. One key prediction for Sr₂RuO₄, a splitting of the superconducting and TRSB transitions under uniaxial stress has not been observed so far. We report a large stress-induced splitting between the onset temperatures of superconductivity and TRSB transitions observed by muon spin relaxation (µSR) measurements under uniaxial stress. To perform these technically challenging experiments, a customized uniaxial pressure cell was developed which will be presented. We also discuss the effect of disorder on the superconducting and TRSB states by µSR, concerning the chirality of the order parameter.
[1] A. Pustogow, et al., arXiv: 1904.00047; K. Ishida et al., arXiv:1907.12236.
[2] C. Hicks, et al., Science 344, 283 (2014), M.Barber, et al., PRL. 120, 076602 (2018).