EFFECTS OF RANDOMNESS AT INTERFACES ON THE EXCHANGE COUPLING IN MAGNETIC MULTILAYERS

The oscillation of the exchange coupling as a function of nonmagnetic layer thickness is studied by calculating the nonlocal susceptibility between magnetic layers. Emphasis is put on the effects of randomness on a microscopic scale at interfaces on the exchange coupling. An expression for the nonlocal susceptibility including the vertex correction is obtained in the single-band tight-binding model. The vertex correction is calculated by a functional-derivative method in order to satisfy the correct conservation law. Numerical results show that the phase and intensity of the oscillation of the exchange coupling are affected by the randomness but the period is almost unaffected. © 1994 The American Physical Society.