Optimized exchange biasing by controlled in situ oxidation

A new, simple method is presented for the preparation of thin Co/CoO bilayers exhibiting considerably improved characteristics of the magnetic behavior and large exchange bias effects. The ultrathin antiferromagnetic layer is formed at room temperature by controlled in situ exposure of a clean metal layer to pure oxygen gas. The exposure amounts only 100–10 000 L at an oxygen pressure of 10−5 mbar. High purity gases can be used. This method allows to maintain optimum ultrahigh vacuum conditions in the preparation chamber which is an indispensable condition for the preparation of complex layer systems.