Experimental study of the influence of edge roughness on magnetization switching in Permalloy nanostructures

Rectangular Permalloy nanostructures with different edge roughness, but the same average width, were fabricated by controlled variations in the exposure conditions of an electron-beam lithography process. The average widths that were studied ranged from 200 to 640 nm. Structures were characterized individually using magneto-optical Kerr effect single-structure nanomagnetometry and scanning electron microscopy on the same structure. Increased edge roughness caused increased coercivity, except for 200-nm-wide structures. Large edge roughness doubled the coercivity of wide (>600 nm) structures. The coercivity of nominally identical structures (same roughness amplitude) differed by up to 20 Oe, suggesting that the specific edge profile influences magnetic switching. (C) 2004 American Institute of Physics.