Switching asymmetries in closely coupled magnetic nanostructure arrays

Cobalt nanostructures (220 and 300 nmx275 nmx30 nm) were fabricated using electron beam lithography into ordered, close proximity (170 nm) arrays. Domain configurations with accompanying hysteresis loops were measured using off-axis electron holography. Measurements were compared to solutions of the Landau-Lifshitz-Gilbert equations. Both exhibit switching asymmetries due to strong intercell coupling and the presence of a field normal to the cell surface. Magnetic domain configurations during switching depended strongly on the initial conditions, as well as the direction of the perpendicular field relative to the in-plane hysteresis-field direction. (C) 1999 American Institute of Physics. [S0003-6951(99)05543-6].