Power-law relaxation decay in two-dimensional arrays of magnetic dots interacting by long-range dipole-dipole interactions

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Mathet, V. | Ferré, J. | Sampaio, L.C. | Hyndman, R. | Meyer, P. | Jamet, J.P. | Gierak, J. | Chappert, C. | Menezes, F. S.De

Edité par CCSD ; American Physical Society -

International audience. The magnetic relaxation of two-dimensional arrays of dipolar coupled magnetic dots has been measured and simulated. Arrays (formula presented) with perpendicular magnetized Co dots (formula presented) were patterned using a high resolution (formula presented) focused ion beam irradiation. Magnetic domain pattern and time relaxation of the dot arrays were investigated using Faraday magneto-optical microscopy. For arrays designed with high irradiation doses (formula presented) the magnetic relaxation of the array proceeds by the magnetization reversal of individual dots and follows a power-law time decay. The long-range character of the dipolar interaction is found to be responsible for magnetic relaxation with a power-law decay. Monte Carlo simulations, based on a modified Ising Hamiltonian, reproduce this time dependence, and show that the power law is not a consequence of either the finite size or the boundary of the arrays, and it is independent of the shape of dots as well.

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