The 2DEG as a non-invasive tool for determining the switching behaviour in cobalt needle arrays

We have investigated magnetic surface superlattices comprising a two-dimensional array of ferromagnetic cobalt needles deposited on top of the GaAs/AlGaAs semiconductor heterostructure. We report that, when the majority of the external field is applied in-plane, along the long axis of the elements, the magnetic switching behaviour of the array is revealed by forming the sum and the difference of the two sets of longitudinal magnetoresistance traces measured from both sides of the Hall-bar.