Hall magnetometry on a ferromagnetic nanoring

We have integrated an individual nanostructured permalloy ring on a Hall sensor and studied the switching processes in a temperature regime between 4.2 and 90 K in in-plane magnetic fields. The nanoring has an outer diameter of 550 nm. In the ring with a small width of 125 nm we find a characteristic two-step switching process in the Hall traces. We show that the switching fields change if we vary the direction of the in-plane field or the temperature. We attribute this to lateral inhomogeneities in the nanoring.