Effect of an exchange tab on the magnetization switching process of magnetic nanowires

We report on a systematic electrical transport study of the effect of an exchange tab on the magnetization switching process of magnetic nanowires. The exchange tab consists of a small segment of a ferromagnetic layer coupled antiferromagnetically to a small portion of the magnetic wire via a thin Ru spacer. The magnetic force microscopy image shows that the exchange tab has a single domain structure. The magnetoresistance of exchange tab stabilized nanowires is characterized by a reversible switching process in both the longitudinal and the transverse field directions. The former is in sharp contrast to the magnetoresistance curve of nanowires with the same geometry but without an exchange tab. The dependence of the exchange field on the tab size has also been investigated, which revealed that a shorter tab generally leads to a stronger coupling between the tab and the nanowire. Micromagnetic modelling has been carried out to interpret the experimental results