Magnetic Assembly and Cross-Linking of Nanoparticles for Releasable Magnetic Microstructures

Abstract

This article describes a versatile method to fabricate magnetic microstructures with complex two-dimensional geometric shapes using magnetically assembled iron oxide (Fe3O4) and cobalt ferrite (CoFe2O4) nanoparticles. Magnetic pole patterns are imprinted into magnetizable media, onto which magnetic nanoparticles are assembled from a colloidal suspension into defined shapes via the shaped magnetic field gradients. The kinetics of this assembly process are studied by evaluation of the microstructure features (e.g., line width and height) as a function of time, particle type, and volume fraction. After assembly, the iron oxide particles are cross-linked in situ and subsequently released by dissolving a sacrificial layer. The free-floating magnetic structures are shown to retain their patterned shape during manipulation with external magnetic fields.

Tuning coercive force by adjusting electric potential in solution processed Co/Pt(111) and the mechanism involved

“…However, due to problems associated with increasing the storage capacity of hard disk drives, the data storage community faces the necessity of exploring and developing new concepts in attempts to increase areal density123. In recent years, extensive efforts have been devoted to exploring alternate approaches for improving the storage density of magnetic recording devices, and include two-dimensional magnetic recording (TDMR)45, heat-assisted magnetic recording (HAMR)6789, microwave-assisted magnetic recording (MAMR)1011, bit-patterned magnetic recording (BPMR)12131415, and optical switching of magnetic domains161718. For instance, a broadband near-field thermal extraction device based on hyperbolic metamaterials can significantly enhance near-field energy transfer by extracting evanescent waves with arbitrarily large lateral wave vectors6.…”

“…Near-field thermal extraction has important practical implications in HAMR68. Free-floating magnetic structures composed of in situ cross-linked magnetically assembled nanoparticles have been reported to retain their patterned shape during manipulation with external magnetic fields12 while a magnetic pattern can serve as an elementary base in magnetic recording media such as BPMR1214. By exploiting the field-confining capability as plasmonic nanoantennas, ferrimagnetic TbFeCo thin films have the potential for use in the optical switching of magnetic domains, while the importance of a chemically homogeneous sample structure is highlighted for optical switching-based recording technologies16.…”

Softening Hard Stool Using Magnetically Controlled Fe3O4 Nanoparticles

“…When the static magnetic field is weaker than the alternating magnetic field, the aggregates with larger length are likely deformed by the oscillating field, as has also been found by many researchers. (28)(29)(30)(31) The swaying amplitude of aggregate L25 is almost linearly dependent on the relative angle between H s and H v , as depicted in Fig. 6(d).…”

Electrochemical plasmonic metamaterials: towards fast electro-tuneable reflecting nanoshutters

“…Various options are being considered: Tuneability via changed thermodynamic conditions and adsorption 1-3 , applied mechanical force and deformation (stretching, bending, and compression) 4,5 , magnetic field 6 , and electrical field [7][8][9] . The latter direction is central for the research team at the Chemistry Department of Imperial College, which explores various scenarios of for electrochemical plasmonics.…”