Micromagnetic behavior of conical ferromagnetic particles

Large area arrays of cobalt and nickel particles with truncated conical sha pes and diameters of 80-120 nm have been prepared using interference lithog raphy combined with an evaporation and lift-off process. The magnetic hyste resis has been measured and the remanent states of the particles have been compared with a three-dimensional micromagnetic model. The model shows a tr ansition from "flower" to "vortex" magnetization states as the particle siz e increases. The distribution of switching fields and the magnetostatic int eractions between particles have been characterized. Both lead to a slow ap proach to saturation in the hysteresis loops. The suitability of such array s for data storage is discussed. (C) 2001 American Institute of Physics.