Perpendicular Exchange Bias and Magnetic Anisotropy in FePt/FeMn Multilayers

A systematic investigation of parallel and perpendicular exchange bias in FePt/FeMn multilayers is presented. Perpendicular magnetic anisotropy observed in FePt/FeMn multilayers is attributed to the surface anisotropy at the interface of FePt/FeMn. The surface and volume anisotropy constants are found to decrease with increasing temperature. The thickness (FePt) dependence of exchange bias field and blocking temperature are discussed. Of interest is the blocking temperature of the parallel exchange bias is higher than that of the perpendicular one, which is qualitatively explained by assuming that the spins at the FePt/FeMn are tilted