QUANTUM-THEORY OF SPIN-WAVES FOR MAGNETIC-OVERLAYER SYSTEMS .2. EFFECT OF MAGNETIC-STRUCTURES

Spin waves in magnetic-overlayer structures formed by thin overlayers on top of a substrate are considered in this paper. The coupling betwe en spins is the Heisenberg exchange interaction. The magnetic structur es of the composite materials are taken to be different from each othe r. Two systems are considered: (1) ferromagnetic overlayers on an anti ferromagnetic substrate; (2) antiferromagnetic overlayers on a ferroma gnetic substrate. In obtaining the energy dispersion relations of spin waves, we employed a Green's-function formalism and introduced transf er functions between successive atomic layers. It is shown that a simp le algorithm can be established between the transfer functions, which can greatly simplify the numerical analysis of Green's functions. The energy of surface states is calculated and the existence of resonant s tates is discussed.