Oscillatory biquadratic antiferromagnet/ferromagnet interface exchange coupling

A study of the influence of roughness at an antiferromagnet (AFM)/ferromagnet (FM) interface on the magnetic exchange coupling in epitaxial Co(0 0 1)/FCT-Mn(0 0 1) bilayers is presented. Co atomic monolayer thickness oscillations of the coercivity (HC) and the exchange bias (HE) are observed, which are clearly related to the modulated interface step density caused by the layer-by-layer growth mode of the Co(0 0 1) template films. Simulations based on a Stoner-Wohlfarth model suggest the existence of a strong intrinsic orthogonal coupling of the AFM/FM interface spins. This interaction is distinctly weakened by an increased interface roughness.