Magnetic properties of superlattices formed from ferromagnetic and antiferromagnetic materials

We present theoretical studies of basic magnetic response characteristics of superlattice structures formed from alternating layers of ferromagnetic and antiferromagnetic materials, each described through use of a localized spin model. The geometry explored here is one in which the antiferromagnet consists of sheets parallel to each interface within which the spins are aligned ferromagnetically. The study of the classical (mean-field) ground state as a function of magnetic field shows that a sequence of spin-reorientation transitions occur, particularly for superlattices within which the antiferromagnetic constituent consists of an even number of layers. For the various phases, we present calculations of the spin-wave spectrum, and also the infrared absorption spectrum.