Magnetoresistance based first-order reversal curve analysis of magnetic tunnel junctions

First-order reversal curve (FORC) analysis is conventionally applied to magnetization versus applied magnetic field loops to determine the ensemble properties of multidomain magnetic samples ranging from naturally occurring geological samples to exquisitely engineered materials for use in magnetic storage. We apply FORC analysis to magnetic tunnel junctions (MTJs) by using magnetoresistance instead of magnetization field. By using the MTJ resistance to monitor domain switching, arbitrarily small samples can be studied, as well as functioning devices after lithographic patterning. Experimental data are presented from sub-0.01 mm2 MTJs that illustrate the application of FORC analysis and demonstrate asymmetric switching distributions when mapped in coercive versus interaction field space.