A decrease in the exchange bias caused by an increase in the effective thickness of the copper layer in the NiFe/Cu/IrMn heterostructures

In a series of NiFe/Cu/IrMn structures with variable effective thickness of the nonmagnetic copper interlayer (up to its absence in the NiFe/IrMn sample), decrease the exchange bias and coercivity caused by increase in the effective thickness of the copper layer is observed. Merger of copper islands at the 1 nm effective Cu thickness replaces direct exchange interaction between the ferromagnetic NiFe and antiferromagnetic IrMn to indirect exchange interaction provided by the conduction electrons through the copper layer NiFe–Cu–IrMn. The structural quality of single crystalline ferro- and antiferromagnetic layers does not undergo any change and magnetization reversal happens by coherent rotation of magnetization in the all analyzed temperature range 2 – 300 K. Simulation of the dynamics of Cu deposition demonstrates the island structure of the film at the initial stages up to effective thickness 1 nm.