To investigate spin susceptibility in a superconducting (SC) state, we measured the Te125-NMR Knight shifts at magnetic fields (H) up to 6.5 T along the b and c axes of single-crystal UTe2, a promising candidate for a spin-triplet superconductor. In the SC state, the Knight shifts along the b and c axes (Kb and Kc, respectively) decreased slightly, and the decrease in Kb was almost constant up to 6.5 T. The reduction in Kc decreased with increasing H, and Kc 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 d-vector state within the spin-triplet scenario and suggest that the dominant d-vector component for the case of Hb changes above 13 T, where Tc increases with increasing H.
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