  The putative spin-triplet superconductor UTe2 has an Ising-like magnetic
anisotropy, indicating the Cooper pair spins parallel to the easy-axis.
However, the upper critical field for the hard-axis direction is much larger
than that for the easy-axis, implying the strong suppression of the Pauli
depairing effect even for the hard-axis direction. This observation is
consistent with the recent NMR measurements which show the tiny decrease of the
Knight shift below the transition temperature Tc for hard-axis magnetic fields.
We clarify that these behaviors are naturally understood as a result of
multi-orbital f -electron bands with total angular momentum j=5/2. Taking into
account spin-orbit couplings for an orthorhombic structure, we demonstrate that
for hard-axis magnetic fields, the decrease of the spin susceptibility below Tc
and the Pauli depairing effect are strongly suppressed.
