  Understanding the role of spin-orbit coupling (SOC) has been crucial to
controlling magnetic anisotropy in magnetic multilayer films. It has been shown
that electronic structure can be altered via interface SOC by varying the
superlattice structure, resulting in spontaneous magnetization perpendicular or
parallel to the plane. In lieu of magnetic thin films, we study the similarly
anisotropic helimagnet Cr$_{1/3}$NbS$_2$, where the spin polarization
direction, controlled by the applied magnetic field, can modify the electronic
structure. As a result, the direction of spin polarization can modulate the
density of states, and in turn affect the in-plane electrical conductivity. In
Cr$_{1/3}$NbS$_2$, we found an enhancement of in-plane conductivity when the
spin polarization is out-of-plane, as compared to in-plane spin polarization.
This is consistent with the increase of density of states near the Fermi energy
at the same spin configuration, found from first principles calculations. We
also observe unusual field dependence of the Hall signal in the same
temperature range. This is unlikely to originate from the non-collinear spin
texture, but rather further indicates strong dependence of electronic structure
on spin orientation relative to the plane.
