A Moiré interference pattern formation of magnetic nanoparticles by rotational magnetic field controlled interfacial self-assembly

Abstract

Abstract‘Magic-angled’ structure currently attracts increasing attention from condensed matter physics due to its amazing performance in superconductivity of graphene. The similar pattern formation of nanoparticles will bring about novel physics in nanoscale that causes the next generation nanodevices. However, it remains a challenging task to acquire such patterns by self-assembly process. In this article, we reported a Moiré interference pattern formation of magnetic nanoparticles regulated by a rotational magnetic field. The colloidal concentration, the strength, and the frequency of magnetic field were found to affect the pattern formation. The mechanism lied in a two-step process. First, the magnetic nanoparticles formed bilayers of superlattice driven by hydrophobic interaction of interfacial self-assembly. Then, the bilayers of superlattice yielded asynchronous rotational displacement resulting from the magnetic force so that the Moiré interference pattern of nanoparticles formed. This fabrication methodology based on the field-controlled self-assembly provided a novel and simple means to get ‘magic angled’ structures in nanoscale that will enrich the physical understanding of nanotechnology.

Magnetic nanomaterials mediate precise magnetic therapy

“…Using magnetic nanoparticles based on oleic acid capping, this study demonstrates a new mechanism by which the assembly behavior of such magnetic nanoparticles under the action of an alternating magnetic field is jointly regulated by the relaxation time of the nanoparticles themselves and the frequency of the external magnetic field: when the relaxation time is greater than the external magnetic field period, the particles are attractively interacting with each other and aggregation occurs; when the relaxation time is less than the external magnetic field period, the particles repel each other and instead become more dispersed [44]. We further prepared various ordered structures, including radial [45], parallel strip [46], dot matrix [47], flying saucer-like [48], and magic-angle graphene-like structures [49], which deepened the technical theoretical system of magnetic-field-controlled nanoparticle self-assembly and offered the foundation for the subsequent hydrogel encapsulation of magnetic iron oxide nanostructures for intelligent fabrication.…”