Exchange Interactions in NiFe/Ta/IrMn Heterostructures under Conditions of Tantalum Deficiency

In the NiFe/Ta/IrMn structures, the contributions of two types of exchange interactions at the NiFe/IrMn interface, partially separated by sections of the nonmagnetic tantalum interlayer, are distinguished. One type of exchange is “contact”—it occurs directly at the NiFe/IrMn interface. Another type is “interlayer,” which takes place through the conduction electrons of the tantalum interlayer. A comparison of the temperature dependences of the exchange bias of the hysteresis loops at fixed parameters of the ferromagnetic layers and various effective thicknesses of the nonmagnetic interlayer made it possible to separate the contributions of the above types of exchange interactions and determine their temperature dependences individually. The exchange interaction energies at the NiFe/IrMn and NiFe/Ta/IrMn interfaces were determined.