Giant magnetoresistance in FeRh: A natural magnetic multilayer

We point out that the binary metallic compound FeRh is a naturally occurring magnetic multilayer structure that shows giant changes in electrical resistance when switched from antiferromagnetic to ferromagnetic order by an applied field. The transition from antiferromagnetic to ferromagnetic coupling and the associated drop in resistance are similar properties to those of fabricated magnetic multilayer structures. The simple crystal structure makes possible a reliable calculation of the magnetic structure of FeRh from first-principles total-energy electronic-structure calculations, which show that the ground state is type-II antiferromagnetism and that there is a metastable ferromagnetic state that is accessible by an applied magnetic field. © 1992 The American Physical Society.