Inhomogeneous Knight shift in vortex cores of superconducting FeSe

We report $^{77}$Se NMR data in the normal and superconducting states of a single crystal FeSe for several different field orientations. The Knight shift is suppressed state in-plane fields, but does not vanish at zero temperature. For fields oriented out plane, little or no reduction observed below $T_c$. These results reflect spin-singlet pairing emerging from nematic with large orbital susceptibility spin-orbit coupling. spectra spin-relaxation rate reveal electronic inhomogeneity that enhanced state, possibly arising density vortex cores. Despite spin polarization these states, there evidence antiferromagnetic fluctuations.