Anisotropic response of spin susceptibility in the superconducting state of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>UTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> probed with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Te</mml:mi><mml:mprescripts/><mml:none/><mml:mn>125</mml:mn></mml:mmultiscripts><mml:mtext>−</mml:mtext><mml:mi>NMR</mml:mi></mml:mrow></mml:math> measurement
Genki Nakamine, Katsuki Kinjo, Shunsaku Kitagawa, K. Ishida, Y. Tokunaga, H. Sakai, S. Kambe, Ai Nakamura, Yusei Shimizu, Yoshiya Homma, Dexin Li, Fuminori Honda, Dai Aoki
Abstract
To investigate spin susceptibility in a superconducting (SC) state, we measured the $^{125}\mathrm{Te}$-NMR Knight shifts at magnetic fields ($H$) up to 6.5 T along the $b$ and $c$ axes of single-crystal ${\mathrm{UTe}}_{2}$, a promising candidate for a spin-triplet superconductor. In the SC state, the Knight shifts along the $b$ and $c$ axes (${K}_{b}$ and ${K}_{c}$, respectively) decreased slightly, and the decrease in ${K}_{b}$ was almost constant up to 6.5 T. The reduction in ${K}_{c}$ decreased with increasing $H$, and ${K}_{c}$ was unchanged through the SC transition temperature at 5.5 T, excluding the possibility of spin-singlet pairing. Our results indicate that spin susceptibilities along the $b$ and $c$ axes slightly decrease in the SC state in low $H$, and the $H$ response of SC spin susceptibility is anisotropic on the $bc$ plane. We discuss the possible $\mathbit{d}$-vector state within the spin-triplet scenario and suggest that the dominant $\mathbit{d}$-vector component for the case of $H\ensuremath{\parallel}b$ changes above 13 T, where ${T}_{\mathrm{c}}$ increases with increasing $H$.