Single-domain circular nanomagnets

The magnetic properties of deep submicron circular nanomagnets fabricated b y high-resolution electron beam lithography from Supermalloy (Ni80Fe14Mo5) have been studied as a function of both diameter (500-55 nm) and thickness (6-15 nm). A high sensitivity magneto-optical method has been used to measu re the hysteresis loops of these nanomagnets. An experimental phase diagram in diameter and thickness has thus been produced which identifies a vortex phase and a single-domain phase. The two phases agree well with micromagne tic theory.