Training effects and the microscopic magnetic structure of exchange biased Co/CoO211 bilayers

摘要

Exchange bias of a partially oxidized thin film of ferromagnetic Co was studied211u001eby magnetization measurements and polarized neutron reflectivity (PNR). The 211u001emagnetization curve shows strong effects of training with cycling of the magnetic 211u001efield. Reflectivity measurements with the field parallel to the cooling field 211u001eshowed the onset of spin-dependent diffuse scattering--off the specular 211u001ereflection--after a training cycle. Such scattering, of the Yoneda type, is due 211u001eto misaligned Co domains possibly close to the Co/CoO interface. Subjecting the 211u001efield cooled Co/CoO pair to a field perpendicular to the cooling field causes a 211u001erotation of the magnetization. PNR measurements confirmed earlier susceptibility 211u001estudies by indicating that the rotation of the magnetization is reversible in 211u001efields up to 400 Oe. The rotation of the magnetization of Co is uniform across 211u001ethe film thickness.