High-yield large scale laser patterning of magnetic nanoparticles

Abstract Patterned magnetic nanoparticles are key elements for magnetic devices. This article reports a laser based approach to generate patterns of magnetic nanoparticles over a large area at high yield. The local hot spot of a tightly focused laser can induce rapid in situ oxidation of iron salts adsorbed on a porous silica substrate into magnetic iron oxide nanoparticles, as confirmed by reflectance test, Raman spectroscopy, electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and magnetic measurement. The effects of laser power, moving speed and laser frequency on the formation (mass and line width) of patterned magnetic nanoparticles have been examined. Given high yield of laser oxidation and high speed of laser direct patterning, the method is appropriate to produce magnetic material pattern over a large area.