Angular dependence of spin-torque critical currents for CPP-GMR read heads

This paper discusses the theoretical aspects and experimental measurement of the angular dependence of the spin-torque critical currents in current perpendicular-to-plane (CPP)-GMR heads. Experimental measurements were made of E-beam lithographically defined circular pillars of all-metal CPP-GMR spin valves. The field-dependent critical current was measured from the onset of obvious deviations from the low voltage curves. RF magnetic noise vs bias current were also taken. The result can have important implication of the choice of the optimum bias current polarity for practical application of all-metal CPP spin-valve read heads.