Domain structure in magnetic dots prepared by nanoimprint and e-beam lithography

Square arrays of silicon dots with feature sizes from 30 to 400 nm and periodicities from 60 to 500 nm were obtained by standard lithography or nanoimprint and reactive ion etching. Co/Pt multilayers with perpendicular anisotropy were subsequently deposited by magnetron sputtering onto these prepatterned wafers. The deposition was performed either at normal or oblique incidence. The magnetic domain structures were characterized by magnetic force microscopy after zero field cooling (ZFC) from the (Co/Pt) Curie temperature or by alternative demagnetization (AD). It appears that the angle of deposition of the Pt influences the existence of direct exchange coupling between neighboring dots due to the formation of a magnetic layer on the sidewalls of the dots. (C) 2002 American Institute of Physics.