Magnetic step regions in alpha-Fe2O3 nanostructured ring arrays

alpha-Fe2O3 nanostructured ring arrays with different ring sizes were fabricated by solution-dipping on a colloidal monolayer template. The magnetic properties of the arrays are investigated. An abnormal magnetic step region was observed in the hysteresis loop at room temperature, showing existence of a steady Vortex state in alpha-Fe2O3 ring arrays at room temperature. However, at a low temperature (50 K), the step region disappeared. Also, no step region is found from Fe ring array with the similar morphology to that of alpha-Fe2O3. This is attributed to the weak dependence of hysteresis loop on size and morphology of the single ring for alpha-Fe2O3 at room temperature. (C) 2007 Elsevier B.V. All rights reserved.