Manchester finds unexpected graphene behaviour

Research at the University of Manchester has shown how by stacking two dimensional materials – graphene and boron nitride for example – they can design new properties – a bandgap for graphene, for example.

Manchester graphene-boron nitride bi-layer

By controlling the relative orientation of graphene and underlying boron nitride, the team can created local strains.

“It was extremely exciting to see that the properties of graphene can change so dramatically by simply twisting the two crystals only a fraction of a degree,” said PhD student Colin Woods. “Generally, the previous model used to describe the sort of interaction which has been observed in our experiments describes only the 1-dimensional case, but even there it produces very non-trivial solutions. We hope that our system will push the mathematical development of the model to two-dimensions, where even more exciting mathematics is to be expected.”

This demonstration of layer interaction in 2d heterostructures is described in a Nature Physics paper: ‘Commensurate–incommensurate transition in graphene on hexagonal boron nitride’, and was led by graphene co-discoverer Sir Kostya Novoselov.

“Research on heterostructures is gaining momentum, and such possibilities for controlling the properties of heterostructures might become very useful for future applications,” said Novoselov.

The next step is to combine several of these crystals in a 3D stack. Already, tunnelling transistors, resonant tunnelling diodes, and solar cells have been made.

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