Giant Magnetoresistance by Exchange Springs in DyFe₂/YFe₂ Superlattices

Magnetization and magnetoresistance measurements are reported for antiferromagnetically coupled DyFe$_2$/YFe$_2$ multilayers in fields up to 23 T. We demonstrate that the formation of short exchange springs (~ 2 nm) in the magnetically soft YFe$_2$ layers results in a giant magneto-resistance as high as 32% in the spring region. It is shown that both the magnitude of the effect, and its dependence on magnetic field, are in good agreement with the theory of Levy and Zhang for giant magnetoresistance due to domain wall like structures.