Paramagnetic effects of j-electron superconductivity and application to UTe2

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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Cited by in corpus (10)

• Unconventional Superconductivity in UTe2
• Large Reduction in the $a$-axis Knight Shift on UTe${}_2$ with $T_{\mathrm{c}}$ = 2.1 K
• Superconducting order parameter in UTe${}_2$ determined by Knight shift measurement
• Anisotropic response of spin susceptibility in the superconducting state of UTe${}_2$ probed with ${}^{125}$Te-NMR measurement
• Anapole superconductivity from $\mathcal{P}\mathcal{T}$-symmetric mixed-parity interband pairing
• Field-induced compensation of magnetic exchange as the possible origin of reentrant superconductivity in UTe${}_2$
• Non-unitary triplet superconductivity tuned by field-controlled magnetization --URhGe, UCoGe and UTe${}_2$--
• Anisotropic paramagnetic response of topological Majorana surface states in the superconductor ${\text{UTe}}_2$
• Spin susceptibility of nonunitary spin-triplet superconductors
• $b$-axis and $c$-axis Knight shift measurements in the superconducting state on ultraclean UTe${}_2$ with $T_c$ = 2.1 K