The handedness or "chirality" of electrons affects how current flows in graphene transistors, according to new work done by researchers in the UK and Russia. The team's findings could help to make better graphene-based electronic devices and could even lead to a new technology, dubbed "chiraltronics".
Graphene is a sheet of carbon atoms just one atom thick, arranged in a honeycomb lattice. The material is unique in that each electron moves along the sheet relativistically, as if it had no mass, with a speed of 1000 km/s. These electrons are also "chiral" in that they are either "right-handed" or "left-handed" – they are mirror images of each other. The electronic states that they can occupy are also chiral.
The UK–Russia team has now studied these electrons in detail by looking at the way current flows in a simple structure made up of a four-atom-thick layer of boron nitride (BN), sandwiched between two layers of graphene. When a voltage is applied, more electrons can be added to one of the graphene layers, so that it becomes negatively charged, and electrons are removed from the other layer so that it becomes positively charged. The BN barrier layer is thin enough so that electrons can pass between the graphene layers by quantum tunnelling, giving rise to an electrical current.
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