Superconducting order parameter in UTe${}_2$ determined by Knight shift measurement

Abstract

This study investigates the spin susceptibility in U-based superconductor UTe${}_2$ in the superconducting (SC) state by using Knight shift measurements for a magnetic field $H$ along the $a$ axis, which is the magnetic easy axis of UTe${}_2$. Although a tiny anomaly ascribed to the SC diamagnetic effect was observed just below the SC transition temperature $T_{\mathrm{c}}$, the $a$-axis Knight shift in the SC state shows no significant decrease, following the extrapolation from the normal-state temperature dependence. This indicates that the spin susceptibility is nearly unchanged below $T_{\mathrm{c}}$. Considering the previous Knight shift results for $H\parallel b$ and $H\parallel c$, the dominant SC state is determined to be $B_{3u}$ in the spin-triplet pairing, which is consistent with the spin anisotropy in the normal state. The present result shows that UTe${}_2$ is a spin-triplet superconductor with spin degrees of freedom.

6 pages, 8 figures

References in corpus (7)

• Unconventional Superconductivity in Heavy Fermion UTe2
• 125Te-NMR Study on a Single Crystal of Heavy Fermion Superconductor UTe2
• Anisotropic response of spin susceptibility in the superconducting state of UTe${}_2$ probed with ${}^{125}$Te-NMR measurement
• Inhomogeneous Superconducting State Probed by ${}^{125}$Te NMR on UTe$_2
• Slow Electronic Dynamics in the Paramagnetic State of UTe${}_2$
• Theory of Pairing Assisted Spin Polarization in Spin-Triplet Equal Spin Pairing: Origin of Extra Magnetization in Sr_2RuO_4 in Superconducting State
• Pressure-temperature phase diagram of ferromagnetic superconductors