Washington: Researchers have discovered a natural 3D counterpart to graphene- the 2D sheets of carbon through which electrons race at many times the speed at which they move through silicon.
The discovery by researchers at the U.S Department of Energy (DOE)`s Lawrence Berkeley National Laboratory (Berkeley Lab) promises exciting new things to come for the high-tech industry, including much faster transistors and far more compact hard drives.
The researchers discovered that sodium bismuthate can exist as a form of quantum matter called a three-dimensional topological Dirac semi-metal (3DTDS). This is the first experimental confirmation of 3D Dirac fermions in the interior or bulk of a material, a novel state that was only recently proposed by theorists.
"A 3DTDS is a natural three-dimensional counterpart to graphene with similar or even better electron mobility and velocity," Yulin Chen said. "Because of its 3D Dirac fermions in the bulk, a 3DTDS also features intriguing non-saturating linear magnetoresistance that can be orders of magnitude higher than the materials now used in hard drives, and it opens the door to more efficient optical sensors."
Chen said the swift development of graphene and topological insulators has raised questions as to whether there are 3D counterparts and other materials with unusual topology in their electronic structure.
He said their discovery answers both questions. In the sodium bismuthate they studied, the bulk conduction and valence bands touch only at discrete points and disperse linearly along all three momentum directions to form bulk 3D Dirac fermions. Furthermore, the topology of a 3DTSD electronic structure is also as unique as those of topological insulators.
This research was supported by the DOE Office of Science and by the National Science Foundation of China.