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Lorentz microscopy study of spin tunnel junction elements

ABSTRACT: Patterned tunnel junction elements with different sizes and aspect ratios have been studied using Lorentz transmission electron microscopy during in-situ magnetisation reversal. The effects of elemental shape and aspect ratio on reversal mechanism have been observed. The reversal field was found to depend strongly on the size and aspect ratio of the elements. 360° domain walls were often observed to form in the elements and were sustained to a high field when the relative magnetisation configuration of the free and pinned layers changed from parallel to antiparallel. The formation of a 360° domain wall depends strongly on elemental shape and aspect ratio. It is believed that the effective coupling is responsible for the formation of 360° domain walls.