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

• We systematically prepared IrMn-based tunneling magnetoresistance (TMR) film stacks, (IrMn/CoFe/Ru/CoFe/CoFeB/MgO/CoFeB) with seed layers of Ta, Ta/Ru, NiFeCr and Ta/NiFe to investigate the impact of seed layer on exchange bias field and TMR ratio. • The magnetic tunnel junctions (MTJs) with seed layers of Ta/Ru and Ta/NiFe have high exchange bias fields, which results from the high-quality (1 1 1) texture of the IrMn layer in these film stacks. • The TMR ratio for the film stack with seed layer of Ta/Ru is much higher than that of the film stacks with other seed layers, which is probably due to the weak interdiffusion at the interfaces of CoFeB/MgO/CoFeB. • Ta/Ru seed layer can facilitate the improvement of TMR ratio, which is beneficial for exploring high-performance spintronic devices such as magnetic field sensor towards high sensitivity and high stability. The exchange bias field (H ex) 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. [ABSTRACT FROM AUTHOR]