Nanopatterning of "hard" magnetic nanostructures via dip-pen nanolithography and a sol-based ink

A direct-write method for fabricating "hard" magnetic barium hexaferrite, BaFe12O19 (BaFe), nanostructures, based on dip-pen nanolithography and a sol-gel process, is presented. This method utilizes a conventional atomic force microscope tip, coated with the BaFe precursor solution, to generate patterns that can be post-treated at elevated temperature to generate magnetic features consisting of barium ferrite in its hexagonal magnetoplumbite (M-type) structure. Features ranging from several hundred nm down to below 100 nm were generated and studied using AFM, magnetic force microscopy, and X-ray photoelectron spectroscopy. The approach offers a new way for patterning functional inorganic nanostructures with deliberate control over feature size and shape, as well as interfeature distance and location.