Mechanism of the Exchange Coupling in Transition Metal Magnetic Multilayers

Abstract

A simple analytical model is suggested in which the oscillatory exchange coupling between ferromagnetic layers of a transition metal separated by a non-magnetic metallic spacer is a consequence of the elementary wave mechanics of electrons in the presence of spin-polarizing boundaries. Under these conditions an oscillatory spin polarization is developed in the spacer. The energy of the system is calculated as a function of two variables: the thickness of the spacer and the angle between spin polarizations of the ferromagnets. It is shown that in the absence of the magnetic field the energy at any thickness is minimized by either parallel or antiparallel spin polarizations of the ferromagnets.