Micromagnetic studies of nickel microbars fabricated by nanoimprint lithography and electrodeposition

Micromagnetic configurations and macromagnetic properties of electrodeposited nickel microbars with six different aspect ratios defined by nanoimprint lithography, and their magnetization switching properties along the long axis were investigated. It was found that the magnetization direction depends on the thickness of nickel microbars. In the remanent state, magnetization in microbars with smaller aspect ratios had a predominantly vortex configuration, while microbars with higher aspect ratios were predominantly in a single-domain state. Individual remanent curves, extracted from magnetic force microscopy images for microbars with all aspect ratios, show that in the range of magnetic fields investigated, complete switching of magnetization takes place only in microbars with aspect ratios larger than 2.86. Individual remanent curves were used to construct the net remanent curve, and its agreement with the macroscopic remanent magnetization curve is discussed. The switching mechanism of nickel microbars with rounded corners proceeds through vortex formation, as determined by micromagnetic modeling.