Summary: Journal of Magnetism and Magnetic Materials 320 (2008) 17811786
Field-dependent evolution of magnetic states in Co ring arrays
, J. Wanga
, A.O. Adeyeyea,Ã, N. Singhb
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore,
4 Engineering Drive 3, Singapore 117576, Singapore
Institute of Microelectronics, 11 Science Park Road, Singapore Science Park II, 117685 Singapore, Singapore
Received 22 November 2007; received in revised form 21 January 2008
Available online 11 March 2008
We present a systematic study of field-dependent evolution in the magnetization reversal process of elongated Co ring arrays using in-
situ field magnetic force microscopy. We observed that, the rings typically undergo a uniform-onion-vortex-reverse onion-reverse
uniform spin-state transition as the field is swept along the major axis of the rings. However, the switching field distribution in the arrays
generally leads to each transition occupying a wide range of fields, which results in the observation of coexistence of different
magnetization states at lower field. The magnetization reversal sequence has also been verified by micromagnetic simulations, which
show good agreement with our experimental data.
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