Magnetic Properties of Patterned Co/Pd Nanostructures by E-Beam Lithography and Ga Ion Irradiation

Patterned Co/Pd perpendicular magnetic multilayers using e-beam lithography followed by Ga ion irradiation have been successfully fabricated. Perpendicularly magnetized squared-bits with lateral sizes of 200 to 500 nm were separated by ion-irradiated area. magnetic force microscopy images showed that the most of the patterned squared-bits with size of 200 nm have either uniformly bright or dark magnetic contrasts. Magnetization curves of patterned Co/Pd films were strongly influenced by the bit size and spacing between bits and indicated the existence of exchange coupling between the bits via irradiated spacing. The reduction of exchange stiffness of irradiated area was found to be crucial, to achieve high density in ion-irradiated media