  The spin-orbit interaction in heavy metal/ferromagnet/oxide structures has
been extensively investigated because it can be employed in manipulation of the
magnetization direction by in-plane current. This implies the existence of an
inverse effect, in which the conductivity in such structures should depend on
the magnetization orientation. In this work, we report a systematic study of
the magnetoresistance (MR) of the W/CoFeB/MgO structures and its correlation to
the current-induced torque to the magnetization. We observe that the MR is
independent of the angle between magnetization and current direction, but is
determined by the relative magnetization orientation with respect to the spin
direction accumulated by spin Hall effect, which is the same symmetry of
so-called spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is
considerably larger than those in other structures of Ta/CoFeB/MgO or
Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the
similar W thickness dependence of the MR and the current-induced magnetization
switching efficiency demonstrates that they share the same underlying physics,
which allows one to utilize the MR in non-magnet/ferromagnet structure in order
to understand closely related other spin-orbit coupling effects such as inverse
spin Hall effect, spin-orbit spin transfer torques, etc.
