Intimate relationship between spin configuration in the triplet pair and superconductivity in UTe

松村 拓輝*; 徳永 陽  ; 酒井 宏典   ; 神戸 振作  ; 木俣 基; 他14名*

Matsumura, Hiroki*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Kimata, Motoi; 14 of others*

Spin-triplet superconductivity is an intriguing quantum coherent state with both spin and orbital degrees of freedom, which holds significant potential for future applications in quantum technology. However, how the spin of the triplet pairs responds to an external magnetic field remains poorly understood. This is mainly due to the absence of suitable spin-triplet superconductors. Here, we report results of Knight-shift and ac-susceptibility measurements on UTe. We demonstrate that the spin susceptibility, which slightly decreases compared to the normal-state value below the superconducting transition temperature , is rapidly restored and nearly recovers to the normal-state values around 5 T, well below the SC upper critical field when the magnetic field is applied along the axis.