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arXiv · 2010.05112

Paramagnetic effects of j-electron superconductivity and application to UTe2

Kozo Hiranuma·Satoshi Fujimoto
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Abstract

The putative spin-triplet superconductor UTe2 has an Ising-like magnetic anisotropy, indicating the Cooper pair spins parallel to the easy-axis. However, the upper critical field for the hard-axis direction is much larger than that for the easy-axis, implying the strong suppression of the Pauli depairing effect even for the hard-axis direction. This observation is consistent with the recent NMR measurements which show the tiny decrease of the Knight shift below the transition temperature Tc for hard-axis magnetic fields. We clarify that these behaviors are naturally understood as a result of multi-orbital f -electron bands with total angular momentum j=5/2. Taking into account spin-orbit couplings for an orthorhombic structure, we demonstrate that for hard-axis magnetic fields, the decrease of the spin susceptibility below Tc and the Pauli depairing effect are strongly suppressed.

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Kozo Hiranuma, Satoshi Fujimoto. 2020-10-10. Paramagnetic effects of j-electron superconductivity and application to UTe2. https://doi.org/10.7566/jpsj.90.034707

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