Effect of annealing on the magnetic properties of Cu-capped ultrathin Co films

We report the effect of intermixing of Cu on the magnetic properties of ultrathin Co films deposited on Si(1 0 0). Rutherford backscattering was employed to determine the extent of intermixing, which increased from 7% in an as-grown sample to nearly 23% when annealed at 400 °C. The as-grown sample showed a higher value of magnetization of 530 emu/cm³, which dropped to 20 emu/cm³ on annealing at 400 °C. The low temperature magnetization behavior of the as-grown Co films showed the presence of both positive and negative exchange bias due to the formation of antiferromagentic domains in parallel with ferromagnetic domains. This behavior is explained using the Malozemoff Random Field Model, which predicted values of exchange bias closely matching the present experimental findings.