Structural color originates from the interference of light with periodic structures that feature characteristic length scales on the order of the wavelength of visible light. Long‐range order in photonic structures usually causes iridescence, and increasing disorder renders colors angle‐independent. Random disorder distributes scattering intensity over all wavelengths, producing white in the absence of absorption. Various non‐iridescent, vivid color patterns are found inSternotominilonghorn beetles. Herein,Sternotomis virescensis investigated, where elytral scales produce a green‐blue color pattern on otherwise black elytra. Combining focused ion beam scanning electron microscopy (FIB‐SEM) tomography, ultra‐small‐angle X‐ray scattering (USAXS), structural modeling, and full‐wave optical simulations, it is found that the color originates from amorphous photonic networks based on sub‐units resembling the I‐WP unit cell, a triply‐periodic minimal surface with body‐centered‐cubic symmetry. This work provides insights into how quasi‐order produces stable colors inS. virescenslonghorn beetles, highlights the advantages of volumetric imaging using FIB‐SEM tomography of porous nanostructured materials, and raises interesting questions about the formation mechanisms of amorphous structures in vivo.

Creation of color through photonic morphologies manufactured by molecular self‐assembly is a promising approach, but the complexity and lack of robustness of the fabrication processes have limited their technical exploitation. Here, it is shown that photonic spheres with full‐color tuning across the entire visible spectrum can be readily and reliably achieved by the emulsification of solutions containing a block copolymer (BCP) and two swelling additives. Solvent diffusion out of the emulsion droplets gives rise to 20–150 µm‐sized spheres with an onion‐like lamellar morphology. Controlling the lamellar thickness by differential swelling with the two additives enables color tuning of the Bragg interference‐based reflection band across the entire visible spectrum. By studying five different systems, a set of important principles for manufacturing photonic colloids is established. Two swelling additives are required, one of which must exhibit strong interactions with one of the BCP blocks. The additives should be chosen to enhance the dielectric contrast, and the formation kinetics of the spheres must be sufficiently slow to enable the emergence of the photonic morphology. The proposed approach is versatile and robust and allows the scalable production of photonic pigments with possible future applications in inks for cosmetics and arts, coatings, and displays.

Phase-separated semiconductors containing magnetic nanostructures are relevant systems for the realization of high-density recording media. Here, the controlled strain engineering of Ga$\delta$FeN layers with Fe${}_y$N embedded nanocrystals (NCs) via Al${}_x$Ga${}_{1-x}$N buffers with different Al concentration $0<x_{\mathrm{Al}}<41$% is presented. Through the addition of Al to the buffer, the formation of predominantly prolate-shaped $\epsilon$-Fe${}_3$N NCs takes place. Already at an Al concentration $x_{\mathrm{Al}}$≈ 5% the structural properties—phase, shape, orientation—as well as the spatial distribution of the embedded NCs are modified in comparison to those grown on a GaN buffer. Although the magnetic easy axis of the cubic $\gamma$’-Ga${}_y$Fe${}_{4-y}$N nanocrystals in the layer on the $x_{\mathrm{Al}}=0\%$ buffer lies in-plane, the easy axis of the $\epsilon$-Fe${}_3$N NCs in all samples with Al${}_x$Ga${}_{1-x}$N buffers coincides with the $\left[0001\right]$ growth direction, leading to a sizeable out-of-plane magnetic anisotropy and opening wide perspectives for perpendicular recording based on nitride-based magnetic nanocrystals.

Brilliant colors in nature arise from the interference of light with periodic nanostructures resulting in structural color. While such biological photonic structures have long attracted interest in insects and plants, they are little known in other groups of organisms. Unexpected in the kingdom of Amoebozoa, which assembles unicellular organisms, structural colors were observed in myxomycetes, an evolutionary group of amoebae forming macroscopic, fungal-like structures. Previous work related the sparkling appearance of Diachea leucopodia to thin film interference. Using optical and ultrastructural characterization, we here investigated the occurrence of structural color across 22 species representing two major evolutionary clades of myxomycetes including 14 genera. All investigated species showed thin film interference at the peridium, producing colors with hues distributed throughout the visible range that were altered by pigmentary absorption. A white reflective layer of densely packed calcium-rich shells is observed in a compound peridium in Metatrichia vesparium, whose formation and function are still unknown. These results raise interesting questions on the biological relevance of thin film structural colors in myxomycetes, suggesting they may be a by-product of their reproductive cycle.