Layer thickness dependence of current induced effective fields in ferromagnetic multilayers.

We report the relation between current induced effective fields and ferromagnetic layer thickness. Hall measurements with rotating magnetic field show that the transverse and perpendicular effective fields have linear relations to the inverse of the magnetic moment m per area S. The results imply that both of these effective fields may originate from spin angular momentum transferring. However, the non-zero intercept of the transverse field at m/S=0 implies that magnetization independent effects, such as Rashba effect, may contribute to transverse field. [ABSTRACT FROM AUTHOR]