Manipulation of the time-reversal symmetry breaking superconductivity in Sr₂RuO₄ by uniaxial stress

The symmetry of the unconventional superconducting state of Sr₂RuO₄ continues to be under strong debate [1]. In general, time-reversal-symmetry breaking (TRSB) superconductivity indicates two-component order parameters. Probing Sr₂RuO₄ under uniaxial stress offers the possibility to lift the degeneracy between such components. One key prediction for Sr₂RuO₄, a splitting of the superconducting and TRSB transitions under uniaxial stress has not been observed so far. We report measurements of zero-field muon spin relaxation (μSR) on samples under uniaxial stresses of up to ∼1.05 GPa. We observe a stress-induced splitting between the onset temperatures of superconductivity and TRSB, consistent with qualitative expectations for a chiral order parameter. In addition, we report the appearance of a bulk magnetic order under the uniaxial stress of ∼1.0 GPa [2]. A custom pressure cell was developed to perform μSR under uniaxial stress[3].

References:
[1] Kivelson et al. npj Qua Mat. 5, 43 (2020).
[2] V. Grinenko*, S. Ghosh* et al., https://www.nature.com/articles/s41567-021-01182-7#Abs1.'
[3] S. Ghosh et al., Rev. Sci. Inst. 91, 103902 (2020).
**This work was supported by DFG (GR 4667, GRK 1621, SFB 1143).