Probing magnetization reversal process in ferromagnetic disk by superconductor-ferromagnet junction

We use lateral superconductor (SC)-ferromagnet (FM)-SC device to probe the magnetization reversal process of micron sized FM disk. Upon decreasing external magnetic field from saturated state, a buckling pattern forms first. The onset of buckling pattern and its switching to vortex state are studied with the help of Andreev conductance of the SC-FM interface below the critical temperature (T_c) of SC and the magnetoresistances both below and above the T_c. In the latter case, micromagnetic modeling has been carried out to interpret the experimental results by taking into account the current distributions when the electrodes are at different states.