Andre Geim of the University of Manchester and his colleagues reckon graphite, the slippery soft allotrope of carbon, could lead to a new generation of microelectronic devices. Geim and colleagues laid out graphite sheets one layer at a time to allow them to study the properties of these graphene sheets.
A graphene sheet is electrically conducting, behaving essentially like a two-dimensional metal. But it is a strange kind of metal, with properties dictated by quantum mechanics. For example, even if there are no mobile electrons to carry an electrical current, the electrical conductivity can never fall below a certain minimum value: it is like an electron gate that can never be fully closed.
The Manchester team has shown that graphene can be fashioned into a device called a spin valve, which discriminates between mobile electrons according to their spin. Spin is a quantum-mechanical property of electrons, and can take either of two values — somewhat akin to magnets that can orient their poles in either of two opposed directions. Conventional electronics takes no account of electron spin; but it has been suggested that a spin-dependent form of electronics, called spintronics, could provide new and powerful ways to process information. A graphene spin valve could act rather like a spintronic filter that lets a current pass only if the electrons have the correct spin.
Geim and colleagues announced their findings today at the Institute of Physics’ Condensed Matter and Materials Physics conference at the University of Exeter.