Exchange biasing of oxidized NiFe 81/19

The influence of breaking the vacuum while depositing an exchange coupled multilayer system for a GMR spin valve sensor was investigated, focusing particularly on the relationship between etching time and exchange coupling properties of the antiferromagnet to the ferromagnet. A Cr₄₆Mn₄₆Pt₈ antiferromagnet was used to induce a unidirectional anisotropy in a Ni₈₁Fe₁₉ ferromagnetic layer. Topically, the exchange coupled 30 nm CrMnPt/12 nm NiFe films exhibited an exchange field of approximately 80 Oe by depositing the layers without breaking the vacuum and no consecutive annealing process. Unloading the NiFe layer and exposing it to the air required a sputter etching process before depositing the antiferromagnet to accomplish exchange coupling. For achieving optimal results, the etching time has to match the time required for removing the oxide film but not for etching the NiFe layer any further. However, layer systems deposited by breaking the vacuum displayed a reduction of the exchange field of roughly 50%.