Self-Assembly Magnetic Micro- and Nanospheres and the Effect of Applied Magnetic Fields.

Angelos Mourkas,Angeliki Zarlaha,Nikolaos Kourkoumelis,Ioannis Panagiotopoulos

doi:10.3390/nano11041030

Abstract

The impact of in-plane and perpendicular magnetic fields on the spatial arrangement of superparamagnetic nanospheres is explored. We utilize nanosphere self-organization methods like Spin Coating and Drop-Casting in the presence of magnetic fields. In this way, the additional parameter of the long range magnetic dipolar interactions is introduced to the competing nanosphere–surface and nanosphere–nanosphere interactions, which control order and agglomeration. We present a comparative analysis of the self-assembly characteristics with respect to the different methods and the effect of the applied field in different directions. Under zero field perfect hexagonal arrays can be obtained by spin coating. Parallel applied fields tend to create directional patterns, while perpendicular favor 3D-accumulation.

Highlights

Nanospheres and the Effect of Modern magnetic-material applications require homogeneous microstructures consisting of monodisperse magnetic entities
For the spin coating experiments, we suggest mixing of the initial aqueous so-soTherefore, for the spin coating experiments, we suggest mixing of the initial aqueous lution a asurfactant; is is better suited dip coating experiments similar lutionsolution with awith surfactant; sodium dodecyl sulfate (SDS) SDS
There is no hysteresis, and the curves can be fitted to the Langevin of a vibrating sample magnetometer (VSM) are shown

Summary

Introduction

Nanospheres and the Effect of Modern magnetic-material applications require homogeneous microstructures consisting of monodisperse magnetic entities. Monodisperse nanosphere single-layers that tend to form 2D-hexagonal close packed patterns can be utilized either as templates for the deposition of “nanocaps” or as masks for the formation of triangular-like islands [1,2,3,4]. Crucial microscopic parameters are the centrifugal force, gravity, surface tension, and evaporation rate of the fluid and the substrate’s hydrophilicity. These are controlled by the various solvent and nanosphere concentrations in the solution, the rotation speeds, and use of appropriate surfactants. They achieved high, defect-free, area coverage using variable rotation speed, under constant acceleration, allowing for optimal performance during the different stages of spin coating. A similar methodology had been proposed previously and studied both experimentally and theoretically [9]

Methods

Results

Conclusion