Genuine-2-dimensional magnetism and interlayer magnetic coupling in Fe(110)/Ag(111) multilayers

Abstract We report the observation of genuine two-dimensional ferromagnetism in MBE-grown Fe(110)/Ag(111) multilayers of fixed 3 monolayer (ML) thick Fe components. A linear temperature dependence of the magnetic hyperfine field was observed with transmission Mossbauer spectroscopy in the film whose Ag spacer layer is 20 ML thick. Comparative Mossbauer studies with and without the application of an external magnetic field ruled out the possibility of magnetic relaxation effects as the cause of the observed linear temperature dependence, and thus firmly established that this linear temperature dependence truly represents two-dimensional ferromagnetism. By reducing the thickness of the Ag spacer layer, a weak interlayer magnetic coupling between the Fe layers can be induced. As a result of this weak coupling, the multilayer system behaves three-dimensionally at temperatures sufficiently below a characteristic temperature determined by the strength of the interlayer coupling.