(543h) Iron OXIDE Nanoparticle-Graphene Patterned Interfaces

Abhilasha Dehankar¹, Justin Young², Josh Goldberger³, Ezekiel Johnston-Halperin², Jessica O. Winter^1,4

¹William G. Lowrie Department of Chemical and Biomolecular Engineering, ²Department of Physics, ³Department of Chemistry and Biochemistry, ⁴Department of Biomedical Engineering

Nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), exhibit unique properties because of their small size; and therefore, have significant potential to improve optical, electronic, and magnetic devices. Significant research has occurred in the synthesis of these particles; however, integration of these particles with higher order constructs, as required for device development, remains a challenge. Further, such integration could lead to the development of synergistic structures with novel properties. To harness the full potential of these composites, nanoparticles should be capable of being assembled in a specific, user-defined, and scalable manner on larger film-based materials. Therefore, the broad aim of this research is to develop facile and controlled techniques for generation of nanoparticle-film composites and to study the emergent properties of their interfaces.

As a model system, we are investigating graphene-SPION interfaces. Graphene is a diamagnetic single layer of carbon with excellent electronic properties. However, it lacks intrinsic magnetic ordering, which could be exploited for magneto electronic or spintronic functionality. Existing strategies for generating magnetism in graphene have disrupted native electronic properties. However, recent investigations have shown induced magnetism in graphene without impairing its electronic properties when magnetic materials are placed in close proximity with graphene films[1], [2]. Thus, we deposited SPIONs, which can locally modify the magnetic field felt by charge carriers in the graphene, with the goal of creating ordered assemblies with emergent magnetic properties. As a first approach, we deposited materials through direct deposition and determined that solvent properties significantly influence aggregation state. To create ordered structures, we first encapsulated SPIONs in micelles, that can in turn self-assemble on thin films following Langmuir-Blodgett[3] and spin coating deposition[4]. These materials were characterized using Atomic Force Microscopy (AFM) to evaluate composite surface topography. Magnetic and electronic properties of these composites would be evaluated. Knowledge gained from this research could enable novel 0D-2D interfaces. Similar techniques could be applied to a broad array of nanoparticles and surfaces to generate novel emergent behaviors.

1. Cavalcanti-Adam, E.A., et al., Cell spreading and focal adhesion dynamics are regulated by spacing of integrin ligands. Biophys J, 2007. 92(8): p. 2964-74.

2. Wang, Z., et al., Proximity-induced ferromagnetism in graphene revealed by the anomalous Hall effect. Phys Rev Lett, 2015. 114(1): p. 016603.

3. Spatz, J.P., et al., Ordered Deposition of Inorganic Clusters from Micellar Block Copolymer Films. Langmuir, 2000. 16(2): p. 407-415.

4. Liou, J.-Y. and Y.-S. Sun, Monolayers of Diblock Copolymer Micelles by Spin-Coating fromo-Xylene on SiOx/Si Studied in Real and Reciprocal Space. Macromolecules, 2012. 45(4): p. 1963-1971.