Since its discovery in 2004, the two-dimensional layer of carbon atoms known as graphene has promised to revolutionize materials science, enabling flexible, transparent touch displays, lighter aircraft, cheaper batteries and faster, smaller electronic devices. Now in what could be a key step towards replacing silicon chips in computers, researchers at the University of Manchester have sandwiched two sheets of graphene with another two-dimensional material, boron nitride, to create what they have dubbed a graphene "Big Mac".

The researchers used two layers of boron nitrate to not only separate two graphene layers, but also to see how graphene reacts when it is completely encapsulated by another material. The researchers say this has allowed them, for the first time, to observe how graphene behaves when unaffected by the environment and demonstrates how graphene inside electronic circuits will probably look in the future.

"Creating the multilayer structure has allowed us to isolate graphene from negative influence of the environment and control graphene's electronic properties in a way it was impossible before," said Dr Leonid Ponomarenko. "So far people have never seen graphene as an insulator unless it has been purposefully damaged, but here high-quality graphene becomes an insulator for the first time."

"Leaving the new physics we report aside, technologically important is our demonstration that graphene encapsulated within boron nitride offers the best and most advanced platform for future graphene electronics," added Professor Andre Geim who, along with Professor Kostya Novoselov, was awarded the Nobel Prize for Physics last year for the discovery of graphene at the University of Manchester in 2004.

"It solves several nasty issues about graphene's stability and quality that were hanging for a long time as dark clouds over the future road for graphene electronics. We did this on a small scale but the experience shows that everything with graphene can be scaled up," said Geim. "It could be only a matter of several months before we have encapsulated graphene transistors with characteristics better than previously demonstrated."

The research team's paper, Tunable metal-insulator transition in double-layer graphene heterostructures appears in the journal Nature Physics.