Overview of interlayer exchange theory

Basic mechanisms of interlayer exchange coupling between two ferromagnets separated by a non-magnetic spacer are surveyed. Simple generic theoretical models yielding closed formulae are treated. First, intrinsic exchange between itinerant ferromagnets is treated in the free-electron band approximation, including corrections to the elementary sinusoidal dependences on metallic-spacer thickness and on angle θ included between the magnetic moments. Properties of metallic and insulating spacers are compared. Then three special mechanisms of non-cos θ coupling are described: (1) fluctuations of spacer thickness, (2) loose spins, and (3) a novel phenomenological coupling through a non-normal spacer, possibly acting in spacers composed of chromium or manganese. © 1995.