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arXiv · 2203.08598

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

Hiroki Fujibayashi·Genki Nakamine·Katsuki Kinjo·Shunsaku Kitagawa·Kenji Ishida·Yo Tokunaga·Hironori Sakai·Shinsaku Kambe·Ai Nakamura·Yusei Shimizu·Yoshiya Homma·Dexin Li·Fuminori Honda·Dai Aoki
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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 $T_{\rm c}$, 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 $T_{\rm c}$. Considering the previous Knight shift results for $H \parallel b$ and $H \parallel c$, the dominant SC state is determined to be $B_{\rm 3u}$ 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.

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Hiroki Fujibayashi, Genki Nakamine, Katsuki Kinjo, Shunsaku Kitagawa, Kenji Ishida, Yo Tokunaga, Hironori Sakai, Shinsaku Kambe, Ai Nakamura, Yusei Shimizu, Yoshiya Homma, Dexin Li, Fuminori Honda, Dai Aoki. 2022-03-16. Superconducting order parameter in UTe$_2$ determined by Knight shift measurement. https://doi.org/10.7566/jpsj.91.043705

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