Remanent states in periodic antidot permalloy arrays

It has been recently suggested that periodic antidot arrays in magnetic media could be a suitable system for high density data storage because hard axis magnetic switching has remanence and hence, memory. In this work a numerical micromagnetic study of periodic antidot permalloy arrays is presented. Remanent states are obtained after saturation of the sample along the hard axis direction for different antidot sizes w (0.32 mu m less than or equal to w less than or equal to 2.16 mu m) and different separation distances d between antidots (w/2 less than or equal to d less than or equal to 3w). Our micromagnetic model allows us to study these systems beyond the experimental results presently available so that we can explore the high density limit. The signal to noise ratio decreases significantly for separation distances d greater than or equal to w and increases steadily with the antidot size w in the range analyzed. The remanent configurations are similar to the experimental data obtained by scanning Kerr microscopy. (C) 1999 American Institute of Physics. [S0021-8979(99)72708-8].