title: Magnetic Nanoparticle Arrays Self-Assembled on Perpendicular Magnetic Recording Media.
abstract: We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle-nanoparticle interactions to cluster-cluster interactions as opposed to feature-feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials.
authors: Smart State Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA. ramoh87@gmail.com.
authors: Abdul Rahman
authors: AR
authors: Mohtasebzadeh
authors: Smart State Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA. lye@magassemble.com.|MagAssemble, Irmo, SC 29063, USA. lye@magassemble.com.
authors: Longfei
authors: L
authors: Ye
authors: Smart State Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA. crawtm@mailbox.sc.edu.
authors: Thomas M
authors: TM
authors: Crawford
mesh_terms: D058185:Magnetite Nanoparticles / Q000737:chemistry*; D060306:Magnetometry / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D010316:Particle Size
chemical_list: D058185:Magnetite Nanoparticles
keywords: magnetic nanoparticle; magnetophoresis; nanomanufacturing; pattern transfer; perpendicular magnetic recording; self-assembly