Nanoimprint fabrication of micro-rings for magnetization reversal studies

Submicron magnetic ring arrays are fabricated by nanoimprint lithography and lift-off with a tri-layer resist system. Under normal imprint conditions, ring patterns can be replicated one-by-one from the mold and transferred by lift-off with a Co layer thickness varying in the range of 10-100 nm. The in-plane magnetization reversal of the Co rings measured by using magneto-optical Kerr effect reveals both flux closure and near-single domain states which clearly depend on the size and the thickness of the rings. Under low temperature imprint conditions, micro-rings of larger diameters can be obtained with a mold pattern of circular disks. The magnetization reversal of these rings is also affected by the flux closure process but it shows a different behavior compared to that of the submicron rings.