Coupling mechanisms in exchange biased films (invited)

We use an atomistic Heisenberg model in conjunction with the classical Land au Lifshitz equation for the spin motion to study coupling mechanisms betwe en ferromagnetic (FM) and antiferromagnetic (AFM) films. Calculations for C oO/FM illustrate that there are two coupling mechanisms at work, the spin-f lop coupling and an AFM-FM coupling through uncompensated defects. While th e latter accounts for exchange bias and related phenomena, the former gives rise to a large coercivity and perpendicular alignment between FM spins an d AFM easy axis. A combination of the two mechanisms explains apparent disc repancies between reversible and irreversible measurements of the AFM-FM co upling. (C) 1999 American Institute of Physics. [S0021-8979(99)31508-5].