Magnetic properties of ferromagnet-antiferromagnet superlattice structures with mixed-spin antiferromagnetic sheets

Abstract

We present theoretical studies of the properties of superlattices constructed by alternating films of ferromagnetic and antiferromagnetic materials, each described through use of a localized spin model. The interface between the ferromagnetic and antiferromagnetic constituents is a (110) surface of a bcc lattice. For this system, this geometry places mixed-spin antiferromagnetic sheets adjacent to the ferromagnetic films. The study of the classical ground state as a function of external magnetic field shows that in zero field the ground state has spins canted to minimize total exchange energy at the interface. We find that a different sequence of magnetic-field-induced spin-reorientation transitions occur for various values of the interface exchange constant. For the various phases, we present calculations of the spin-wave spectrum and the infrared absorption spectrum of the superlattice structure.