Oxygen-induced exchange-coupling reversal at the Mn-Co interface

Abstract
We report on a phenomenon associated with surface magnetism: the reversal of exchange coupling induced by oxidation. Ferromagnetically ordered submonolayer films of Mn grown on fcc Co(001) have their magnetization direction oriented parallel to the Co magnetization. After oxygen exposure the Mn atoms remain ferromagnetically ordered but their magnetization direction rotates 180° and is now aligned antiparallel to the Co magnetization. This behavior in magnetic coupling between the Mn and Co films is not consistent with recent theoretical predictions. This difference is perceived to lie in the atomic scale morphology at the Mn-Co interface.