Herein, we report the formation of a particular core–shell structure, with a zinc germanate (Zn2GeO4) nanowire core and a discontinuous shell of SnO2 nanocrystals, obtained in a single-step process. We propose a growth model that combines the Plateau–Rayleigh mechanism to produce a pattern of amorphous germanium oxide (a-GeO2) particles along the Zn2GeO4 nanowire and the subsequent growth of well-faceted SnO2 crystals when the nanowire orientation meets good lattice matching conditions. In this latter case, the linear array of a-GeO2 particles acts as nucleation sites for the SnO2 crystallites, leading to a skewer-like morphology that retains the periodicity of the Plateau–Rayleigh process. Otherwise, nanowires with different orientations appear decorated with a pattern of a-GeO2 beads mimicking a necklace. Atomic resolution electron microscopy has been used to characterize the Zn2GeO4/SnO2 nanoheterostructures. In addition, optical confinement effects have been observed in the luminescence maps and spectra, which have potential for further exploitation in the design of optical microcavities.

Diverse emergent correlated electron phenomena have been observed in twisted-graphene layers. Many electronic structure predictions have been reported exploring this new field, but with few momentum-resolved electronic structure measurements to test them. We use angle-resolved photoemission spectroscopy to study the twist-dependent (1° < θ < 8°) band structure of twisted-bilayer, monolayer-on-bilayer, and double-bilayer graphene (tDBG). Direct comparison is made between experiment and theory, using a hybrid k·p model for interlayer coupling. Quantitative agreement is found across twist angles, stacking geometries, and back-gate voltages, validating the models and revealing field-induced gaps in twisted graphenes. However, for tDBG at θ = 1.5 ± 0.2°, close to the magic angle θ = 1.3°, a flat band is found near the Fermi level with measured bandwidth E w = 31 ± 5 meV. An analysis of the gap between the flat band and the next valence band shows deviations between experiment (Δh = 46 ± 5 meV) and theory (Δh = 5 meV), indicative of lattice relaxation in this regime.