Theory of strain-induced magnetic order and splitting of Tc and TTRSB in Sr2Ru O4

Rømer, A.T. and Kreisel, A. and Müller, M.A. and Hirschfeld, P.J. and Eremin, I.M. and Andersen, B.M.

Volume: 102 Pages:
DOI: 10.1103/PhysRevB.102.054506
Published: 2020

The internal structure of the superconducting state in Sr2RuO4 remains elusive at present, and exhibits evidence for time-reversal symmetry breaking. Recent muon spin relaxation measurements under uniaxial strain have revealed an increasing splitting between the superconducting critical temperature Tc and the onset of time-reversal symmetry breaking TTRSB with applied strain (Grinenko et al., arXiv:2001.08152). In addition, static magnetic order is induced by the uniaxial strain beyond ∼1 GPa, indicating that unstrained Sr2RuO4 is close to a magnetic quantum critical point. Here we perform a theoretical study of the magnetic susceptibility and the associated pairing structure as a function of uniaxial strain. It is found that the recent muon relaxation data can be qualitatively explained from the perspective of spin-fluctuation mediated pairing and the associated strain dependence of accidentally degenerate pair states in unstrained Sr2RuO4. In addition, while unstrained Sr2RuO4 features mainly (2π/3,2π/3) magnetic fluctuations, uniaxial strain promotes (π,±π/2) magnetic order. © 2020 American Physical Society.

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