Influence of seed layer on the magnetoresistance properties in IrMn-based magnetic tunnel junctions

The exchange bias field (Hex) and tunneling magnetoresistance (TMR) ratio play an important role for the applications of magnetic tunnel junction (MTJ) in spintronic devices. Here the structure, magnetic properties, and TMR ratio are systematically investigated for the IrMn-based MTJ (IrMn/CoFe/Ru/CoFe/CoFeB/MgO/CoFeB) with seed layers of Ta, Ta/Ru, NiFeCr and Ta/NiFe. The MTJs with seed layers of Ta/Ru and Ta/NiFe present high H-ex values, and the MTJ with seed layer of Ta/Ru shows the highest TMR ratio. We found that the H-ex is positively correlated with the (1 1 1) texture quality of the IrMn layer while the interdiffusion at the interfaces of CoFeB/MgO/CoFeB has significant impact on the TMR ratio. These results highlight the crucial role of seed layers on the H-ex and TMR ratio, and suggest that the Ta/Ru seed layer is beneficial to developing MTJ-based spintronic devices such as magnetic field sensor towards high sensitivity and high stability.

Automated summary

Seed layers have a significant impact on the exchange bias field and tunneling magnetoresistance ratio of magnetic tunnel junctions (MTJs). The Ta/Ru seed layer is beneficial for developing MTJ-based spintronic devices with high sensitivity and high stability.