|Dec 23, 2019|
Researchers break the geometric limitations of moire pattern in graphene heterostructures(Nanowerk News) Researchers at The University of Manchester have uncovered interesting phenomena when multiple two-dimensional materials are combined into van der Waals heterostructures (layered ‘sandwiches’ of different materials).
|These heterostructures are sometimes compared to Lego bricks – where the individual blocks represent different atomically thin crystals, such as graphene, and stacked on top of each other to form new devices.|
|Published in Science Advances ("Composite super-moiré lattices in double-aligned graphene heterostructures"), the team focus on how the different crystals begin to alter one another’s fundamental properties when brought into such close proximity.|
|Fourier transformation of an AFM image of moiré patterns, showing two sets of distinct hexagonal patterns (red and green dashed hexagons).|
|Of particular interest is when two crystals closely match and a moiré pattern forms. This moiré pattern has been shown to affect a range of properties in an increasing list of 2D materials. However, typically the geometry of the moiré pattern places a restriction on the nature and size of the effect.|
|A moiré pattern is due to the mismatch and rotation between the layers of each materials which produces a geometric pattern similar to a kaleidoscope.|
|The team have broken this restriction by combining moiré patterns into composite ‘super-moiré’ in graphene both aligning to substrate and encapsulation hexagonal boron nitride.|
|The researchers demonstrate the nature of these composite super-moiré lattices by showing band structure modifications in graphene in the low-energy regime. Furthermore, they suggest that the results could provide new directions for research and devices fabrication.|
|Zihao Wang and Colin Woods authors of the paper said: “In recent years moiré pattern have allowed the observation of many exciting physical phenomena, from new long-lived excitonic states, Hofstadter’s Butterfly, and superconductivity.|
|Our results push through the geometric limitation for these systems and therefore present new opportunities to see more of such science, as well as new avenues for applications.”|
|Source: University of Manchester|
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