Large planar Hall effect in perpendicularly magnetized W/CoFeB/MgO structures

•A large planar Hall effect is observed in W/CoFeB/MgO samples.•We examine the variation of the planar Hall effect with different CoFeB thickness.•The planar Hall effect is insensitive to the CoFeB thickness.•The large planar Hall effect is attributed to the strong spin-orbit coupling of the W.

The planar Hall effect (PHE) in W/CoFeB/MgO structure with perpendicular magnetic anisotropy was investigated as a function of CoFeB thickness (tCoFeB). The PHE is measured by sweeping the in-plane magnetic field at various azimuthal angles as well as by rotating strong magnetic field which is enough to saturate the magnetization. We observed a huge PHE in the W/CoFeB/MgO sample, which is even larger than anomalous Hall effect (AHE). This is distinct from the results in Ta/CoFeB/MgO samples showing a much smaller PHE than AHE. Since the PHE is insensitive to the tCoFeB while the AHE is proportional to the tCoFeB, the unprecedented PHE can be attributed to the W layer with a large spin-orbit coupling.