Self-assembled plasmonic metamaterials

Abstract

Nowadays for the sake of convenience most plasmonic nanostructures are fabricated by top-down nanofabrication technologies. This offers great degrees of freedom to tailor the geometry with unprecedented precision. However, it often causes disadvantages as well. The structures available are usually planar and periodically arranged. Therefore, bulk plasmonic structures are difficult to fabricate and the periodic arrangement causes undesired effects, e.g., strong spatial dispersion is observed in metamaterials. These limitations can be mitigated by relying on bottom-up nanofabrication technologies. There, self-assembly methods and techniques from the field of colloidal nanochemistry are used to build complex functional unit cells in solution from an ensemble of simple building blocks, i.e., in most cases plasmonic nanoparticles. Achievable structures are characterized by a high degree of nominal order only on a shortrange scale. The precise spatial arrangement across larger dimensions is not possible in most cases; leading essentially to amorphous structures. Such self-assembled nanostructures require novel analytical means to describe their properties, innovative designs of functional elements that possess a desired near-and far-field response, and entail genuine nanofabrication and characterization techniques. Eventually, novel applications have to be perceived that are adapted to the specifics of the self-assembled nanostructures. This review shall document recent progress in this field of research. Emphasis is put on bottom-up amorphous metamaterials. We document the state-of-the-art but also critically assess the problems that have to be overcome.

Two‐Step Assembly of Thermoresponsive Gold Nanorods Coated with a Single Kind of Ligand

“…[11] In particular, assembled structures composed of colloidal metal nanoparticles show collective optical and magnetic functions. [12][13][14] In the case of metal colloids, chemical properties controlled by surface modification and the shape of the metal core determine the assembled structure. For example, linear, [15,16] periodic arrays, [17][18][19] vesicles, [20][21][22] and superlattice structures [23,24] have all been reported.…”

“…While biomaterials, including proteins, are constructed based on organic molecules, artificially programmed self‐assembly, which can also utilize inorganic materials, enables the creation of novel functional materials, such as metamaterials . In particular, assembled structures composed of colloidal metal nanoparticles show collective optical and magnetic functions . In the case of metal colloids, chemical properties controlled by surface modification and the shape of the metal core determine the assembled structure.…”

Predicting Observable Quantities of Self-Assembled Metamaterials from the T-Matrix of Its Constituting Meta-Atom

“…While considering a sufficiently diluted ensemble of meta-atoms where nearest neighbour interaction is negligibly small, only for the special case of isotropic meta-atoms the response of the ensemble can be directly deduced from the response of the constituent [ 35 , 36 ]. For a sufficiently small particle that justifies a consideration in the dipolar regime, observable quantities have been expressed in term of respective polarizabilities [ 37 ].…”

Dynamically self-assembled silver nanoparticles as a thermally tunable metamaterial

“…S elf-assembly (SA) of nanoparticles (NPs) into ordered structures is a formidable challenge in many branches of material science, especially for metamaterials research [1][2][3][4] . Beyond being fascinating from an intellectual perspective, selfassembled metamaterials provide a clear solution to some open problems that have to be solved before metamaterials can evolve to a mature technology.…”