Nov 29, 2018
(Nanowerk News) A simple sheet of graphene has noteworthy properties due to a quantum phenomenon in its electron structure named Dirac cones in honor of British theoretical physicist Paul Dirac (1902-1984), who was awarded the Nobel Prize for Physics in 1933.
The system becomes even more interesting if it comprises two superimposed graphene sheets, and one is very slightly turned in its own plane so that the holes in the two carbon lattices no longer completely coincide.
For specific angles of twist, the bilayer graphene system displays exotic properties such as superconductivity (zero resistance to electrical current flow).
Theoretical physics discovery paves the way for future technological applications. (Image: Jose Lado)
A new study conducted by Brazilian physicist Aline Ramires with Jose Lado, a Spanish-born researcher at the Swiss Federal Institute of Technology (ETH Zurich), shows that the application of an electrical field to such a system produces an effect identical to that of an extremely intense magnetic field applied to two aligned graphene sheets.
An article on the study has recently been published in Physical Review Letters ("Electrically Tunable Gauge Fields in Tiny-Angle Twisted Bilayer Graphene") and was selected to feature on the issue's cover.
Ramires is a researcher at São Paulo State University's Institute of Theoretical Physics (IFT-UNESP) and the South American Institute for Fundamental Research (ICTP-SAIFR). She is supported by São Paulo Research Foundation - FAPESP through a Young Investigator grant.
"I performed the analysis, and it was computationally verified by Lado," Ramires told. "It enables graphene's electronic properties to be controlled by means of electrical fields, generating artificial but effective magnetic fields with far greater magnitudes than those of the real magnetic fields that can be applied."
The two graphene sheets must be close enough together for the electronic orbitals of one to interact with the electronic orbitals of the other, she explained.
This means a separation as close as approximately one angstrom (10-10 meter or 0.1 nanometer), which is the distance between two carbon atoms in graphene.
Another requirement is a small angle of twist for each sheet compared to the other - less than one degree (α
Theoretical physics discovery paves the way for future technological applications. (Image: Jose Lado)
A new study conducted by Brazilian physicist Aline Ramires with Jose Lado, a Spanish-born researcher at the Swiss Federal Institute of Technology (ETH Zurich), shows that the application of an electrical field to such a system produces an effect identical to that of an extremely intense magnetic field applied to two aligned graphene sheets.
An article on the study has recently been published in Physical Review Letters ("Electrically Tunable Gauge Fields in Tiny-Angle Twisted Bilayer Graphene") and was selected to feature on the issue's cover.
Ramires is a researcher at São Paulo State University's Institute of Theoretical Physics (IFT-UNESP) and the South American Institute for Fundamental Research (ICTP-SAIFR). She is supported by São Paulo Research Foundation - FAPESP through a Young Investigator grant.
"I performed the analysis, and it was computationally verified by Lado," Ramires told. "It enables graphene's electronic properties to be controlled by means of electrical fields, generating artificial but effective magnetic fields with far greater magnitudes than those of the real magnetic fields that can be applied."
The two graphene sheets must be close enough together for the electronic orbitals of one to interact with the electronic orbitals of the other, she explained.
This means a separation as close as approximately one angstrom (10-10 meter or 0.1 nanometer), which is the distance between two carbon atoms in graphene.
Another requirement is a small angle of twist for each sheet compared to the other - less than one degree (α