Observation of spin structure related positive magnetoresistance in antiferromagnetically coupled magnetic multilayers

We report the observation of a previously unobserved positive magnetoresistance effect in several antiferromagnetically coupled magnetic multilayers. The effect is typically very small with the largest magnetoresistance values observed of less than 0.1% at 4.2 K. We find that the effect is common in magnetic multilayers comprised of magnetic layers of Fe and Co and spacer layers composed of elements from the left hand portions of the 4d and 5d transition metal periods. We propose the magnetoresistance is a consequence of Lorentz magnetoresistance and is unrelated to the giant magnetoresistance effect observed in related structures.