Knight Shift and Leading Superconducting Instability from Spin Fluctuations in ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$

Journal Article · Fri Dec 13 00:00:00 EST 2019 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.123.247001· OSTI ID:1603844

Rømer, A. T. ^[1]; Scherer, D. D. ^[2]; Eremin, I. M. ^[3]; Hirschfeld, P. J. ^[4]; Andersen, B. M. ^[2]

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1. Univ. of Copenhagen (Denmark); Institut Laue-Langevin (France); U. Florida Dept. of Physics
2. Univ. of Copenhagen (Denmark)
3. Ruhr-Universität Bochum (Germany); National Univ. of Science and Technology MISiS, Moscow (Germany)
4. Univ. of Florida, Gainesville, FL (United States)

We report that recent nuclear magnetic resonance studies [A. Pustogow et al., Nature 574, 72 (2019)] have challenged the prevalent chiral triplet pairing scenario proposed for ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ . To provide guidance from microscopic theory as to which other pair states might be compatible with the new data, we perform a detailed theoretical study of spin fluctuation mediated pairing for this compound. We map out the phase diagram as a function of spin-orbit coupling, interaction parameters, and band structure properties over physically reasonable ranges, comparing when possible with photoemission and inelastic neutron scattering data information. We find that even-parity pseudospin singlet solutions dominate large regions of the phase diagram, but in certain regimes spin-orbit coupling favors a near-nodal odd-parity triplet superconducting state, which is either helical or chiral depending on the proximity of the $\gamma$ band to the van Hove points. A surprising near degeneracy of the nodal $s^{\text{'}}$ and $d_{x^2-y^2}$ wave solutions leads to the possibility of a near-nodal time-reversal symmetry broken $s^{\text{'}}+i{d}_{x^2-y^2}$ pair state. Lastly, predictions for the temperature dependence of the Knight shift for fields in and out of plane are presented for all states.

• Research Organization: Univ. of Florida, Gainesville, FL (United States)
• Sponsoring Organization: Russian Federation; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: FG02-05ER46236
• OSTI ID: 1603844
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 24 Vol. 123; ISSN 0031-9007; ISSN PRLTAO
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Multiband superconductivity
Pairing mechanisms
Spin-orbit coupling
Superconducting order parameter