Magnetoresistance enhancement in a perpendicular (Co/Pt)4/Co/IrMn/(Co/Pt)2/Co structure

We investigate the magnetoresistance (MR) effect and magnetic properties in (Co/Pt)(4)/Co/IrMn (SFM) and (Co/Pt)(4)/Co/IrMn/(Co/Pt)(2)/Co (DFM) structures with (Co/Pt)(4)/Co and (Co/Pt)(2)/Co multilayers having a perpendicular magnetic anisotropy. Despite the exchange bias field, the antiferromagnetic IrMn layer itself influences the coercivity (H-c) and MR differently for both types of structures when the IrMn layer is thin. A suppressed H-c and an enhanced MR in the DFM samples are obtained compared with those in the SFM samples. The maximum MR reaches up to (0.6 +/- 0.1)% when the IrMn thickness (t(IrMn)) of the DFM samples varies from 1.5 to similar to 5 nm, but the MR value of the SFM samples remains (0.1 +/- 0.05)% with the same t(IrMn) range. The suppressed H-c and the enhanced MR in the DFM samples may be due to the formation of an antiferromagnetic-type contact when large antiferromagnetic domains in the IrMn layer are sandwiched by (Co/Pt)(4)/Co and (Co/Pt)(2)/Co multilayers. Published under an exclusive license by AIP Publishing.

Automated summary

This study investigates the magnetoresistance (MR) effect and magnetic properties in (Co/Pt)(4)/Co/IrMn (SFM) and (Co/Pt)(4)/Co/IrMn/(Co/Pt)(2)/Co (DFM) structures. The research finds that the thickness of the IrMn layer has different effects on the antiferromagnetic and MR properties for these two structures. The DFM structure exhibits suppressed antiferromagnetic property and enhanced MR.