Remanent states in periodic antidot permalloy arrays

It has been recently suggested that periodic antidot arrays in magnetic med ia could be a suitable system for high density data storage because hard ax is magnetic switching has remanence and hence, memory. In this work a numer ical 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). O ur micromagnetic model allows us to study these systems beyond the experime ntal results presently available so that we can explore the high density li mit. The signal to noise ratio decreases significantly for separation dista nces d greater than or equal to w and increases steadily with the antidot s ize 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].