Spin configurations and classification of switching processes in ferromagnetic rings down to sub-100 nm dimensions
Kläui M., Vaz CAF., Monchesky TL., Unguris J., Bauer E., Cherifi S., Heun S., Locatelli A., Heyderman LJ., Cui Z., Bland JAC.
The magnetic states and switching processes are investigated in Co and NiFe rings with lateral dimensions from the micrometer range down to sub-100nm. Using non-intrusive imaging techniques we have directly observed the nanoscopic details of the magnetization configurations of epitaxial and polycrystalline mesoscopic ring structures with < 15 nm resolution. We have found head-to-head domain walls with different spin structures depending on ring width. Further, we can classify the geometry-dependent switching processes according to the number of transitions (single, double, triple) that a ring undergoes in a hysteresis cycle. In the case of triple switching we find a novel state with a complete vortex core present in the ring. It is found that the double switching can be retained in sub-100 nm rings by tailoring the material and thickness. © 2004 Elsevier B.V. All rights reserved.