Current-perpendicular-to-plane giant magnetoresistance in submicron pseudo-spin-valve devices

We measured the transport behavior of Ni₈₀Fe₂₀(Py)∕Cu∕Py current-perpendicular-to-plane (CPP) submicron spin-valve devices with Cu spacer thickness up to 530 nm, fabricated directly from as-grown heterostructures using a three-dimensional focused-ion beam etching technique. The work bridged the gap between existing conventional CPP giant magnetoresistance measurements and lateral type spin-valve experiments. By fitting the data with the Valet-Fert model, we determined the spin asymmetry ratio of 0.80±0.01 and spin diffusion length of 600±245 nm in Cu at 77 K. The magnitude of resistance change obtained in this work was comparable with conventional CPP measurements, but was about two orders of magnitude larger than those of lateral spin-valve devices. The results implied that any success in exploiting the lateral type spintronic devices for practical uses would rely critically on improving the size of the measured signals.