Graphene research has discovered hidden interactions that will affect the way components are designed from the super-fast material.
Scientists from the Georgia Institute of Technology and the US National Institute of Standards and Technology (NIST) have determined how the orbits of electrons interact with magnetic fields applied to epitaxial graphene.
"Understanding such interference will be important for bi-layer graphene devices that have been proposed, and may be important for other lattice-matched substrates used to support graphene and graphene devices," said Professor Phillip First of Georgia Tech.
Findings include that energy states follow contours of constant electric potential, and that there are energy gaps within isolated patches on the surface.
"The regular pattern of energy gaps in the graphene surface creates regions where electron transport is not allowed. Electron waves would have to go around these regions, requiring new patterns of electron wave interference," First explained. "By examining their distribution over the surface for different magnetic fields, we determined that the energy gap is due to a subtle interaction with the substrate, which consists of multilayer graphene grown on a silicon carbide wafer," .
In multi-layer epitaxial graphene, each layer's symmetrical sub-lattice is rotated slightly with respect to the next.
Prior studies, said Georgia Tech, indicated that the rotations decouple the electronic properties of each graphene layer.
"Our findings hold the first indications of a small position-dependent interaction between the layers," said First's colleague David Miller.
Results came from a custom-built scanning-tunnelling microscope at NIST, scanning 100 square nanometre of graphene by taking spectroscopic data every 0.4nm.
According to First, the study raises a number of questions, including whether the new phenomenon can be controlled.
"This study is really a stepping stone in long path to understanding the subtleties of grapheme's interesting properties," he said. "This material is different from anything we have worked with before in electronics."