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arXiv · 1912.02215

Distinct reduction of Knight shift in superconducting state of Sr$_2$RuO$_4$ under uniaxial strain

Austin W. Lindquist·Hae-Young Kee
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Abstract

Shortly after the discovery of superconductivity in Sr$_2$RuO$_4$, spin-triplet pairing was proposed and further corroborated by a constant Knight shift ($K$) across the transition temperature (T$_c$). However, a recent experiment observed a drop in $K$ at T$_c$ which becomes larger under uniaxial strain, ruling out several spin-triplet scenarios. Here we show that inter-orbital spin-triplet pairing features a d-vector that rotates when uniaxial strain is applied, leading to a larger drop in the spin polarization perpendicular to the strain direction, distinct from spin-singlet pairing. We propose that anisotropic spin polarization under strain will ultimately differentiate triplet vs.~singlet pairing.

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Austin W. Lindquist, Hae-Young Kee. 2019-12-04. Distinct reduction of Knight shift in superconducting state of Sr$_2$RuO$_4$ under uniaxial strain. https://doi.org/10.1103/physrevresearch.2.032055

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