Strain-induced time reversal breaking and half quantum vortices near a putative superconducting tetra-critical point in Sr${}_2$RuO${}_4$

Abstract

It has been shown [1] that many seemingly contradictory experimental findings concerning the superconducting state in Sr${}_2$RuO${}_4$ can be accounted for as resulting from the existence of an assumed tetra-critical point at near ambient pressure at which $d_{x^2-y^2}$ and $g_{xy(x^2-y^2)}$ superconducting states are degenerate. We perform both a Landau-Ginzburg and a microscopic mean-field analysis of the effect of spatially varying strain on such a state. In the presence of finite $xy$ shear strain, the superconducting state consists of two possible symmetry-related time-reversal symmetry (TRS) preserving states: $d\pm g$. However, at domain walls between two such regions, TRS can be broken, resulting in a $d+ig$ state. More generally, we find that various natural patterns of spatially varying strain induce a rich variety of superconducting textures, including half-quantum fluxoids. These results may resolve some of the apparent inconsistencies between the theoretical proposal and various experimental observations, including the suggestive evidence of half-quantum vortices [2]. [1] Steven A Kivelson, Andrew C Yuan, BJ Ramshaw, and Ronny Thomale, "A proposal for reconciling diverse experiments on the superconducting state in Sr${}_2$RuO${}_4$," npj Quantum Mater 5 (2020). [2] J Jang, DG Ferguson, V Vakaryuk, Raffi Budakian, SB Chung, PM Goldbart, and Y Maeno, "Observation of half-height magnetization steps in Sr${}_2$RuO${}_4$," Science 331, 186-188 (2011).

18 pages including Appendix, 8 figures

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• High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State
• Observation of half-height magnetization steps in Sr2RuO4
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• Weyl Superconductivity in UTe2
• Half-quantum vortices on c-axis domain walls in chiral p-wave superconductors

Cited by in corpus (3)

• Higher angular momentum pairings in interorbital shadowed-triplet superconductors: Application to Sr${}_2$RuO${}_4$
• Heat capacity double transitions in time-reversal symmetry broken superconductors
• Higher angular momentum pairing states in Sr${}_2$RuO${}_4$ in the presence of longer-range interactions