Suppression of stray field between adjacent rings in one-dimensional ferromagnetic ring arrays

We have investigated the stray field effect among the adjacent rings with different inner diameters in the submicron-sized ferromagnetic ring array. The magnetization reversal process is measured with changing the edge-to-edge distance of the ring array by the magneto-optical Kerr effect. The stray field retains longer distance as the inner diameter decreases. This is due to the reduction of the circumferential shape anisotropy with the smaller inner diameter, where the magnetic moments favor to align along the direction of the one-dimensional array. For the high density storage using ring-shaped magnetic-random access memory, the ring array with the large inner diameter is preferable.