Laterally patterned magnetic nanoparticles

Abstract

Laterally patterning magnetic nanoparticles (MNPs) through self-assembly and simple solution processing constitutes an important step toward inexpensive nanoparticle-based devices. In this work, MNPs were laterally patterned on metal thin films using laterally patterned self-assembled monolayers (SAMs) as a template. SAMs of inactive molecules were first patterned on an Au thin film using the soft-lithographic technique, microcontact printing. The active, bifunctional molecules, 1,10-decanedithiol or 4-(11-mercaptoundecyl)benzene-1,2-diol, were then patterned through backfilling. The MNPs selectively bind to the terminal thiols or modified catechols when the substrates are submerged into a solution of MNPs. By adjusting the deposition conditions, both monolayers and partial multilayers were controllably formed. Co, Ni, Fe₃O₄, and FePt MNPs, as well as Au non-magnetic nanoparticles were successfully patterned by this process. This generalized approach is anticipated to be adaptable to many other kinds of nanoparticlesvia judicious selection of the substrates, surfactant ligands (on the nanoparticle), and/or surface-bound monolayers.