Size-dependent switching of multilayer magnetic elements

Abstract

Pseudo-spin-valve NiFe∕Cu∕NiFe, Co∕Cu∕Co, NiFe∕Cu∕Co films and magnetic tunnel junction films have been patterned into arrays of rectangular elements with widths of 40–140nm and aspect ratios of 1.5–18. The switching field of the hard and soft layers and the interaction field between the layers have been measured as a function of aspect ratio. In the pseudo-spin-valve structures the behavior is dominated by magnetostatic interactions between the layers, leading to antiparallel alignment of the hard and soft layers at remanence for small aspect ratios. Patterned tunnel junction films show weaker magnetostatic effects, and the exchange bias from the antiferromagnetic layer is preserved on patterning.