A easy sheet of graphene has noteworthy properties resulting from a quantum phenomenon in its electron construction 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 turns into much more fascinating if it contains two superimposed graphene sheets, and one could be very barely turned in its personal airplane in order that the holes in the 2 carbon lattices not fully coincide.
For particular angles of twist, the bilayer graphene system shows exotic properties resembling superconductivity (zero resistance to electrical present stream).
A brand new research carried out by Brazilian physicist Aline Ramires with Jose Lado, a Spanish-born researcher on the Swiss Federal Institute of Technology (ETH Zurich), reveals that the applying of field to such a system produces an impact an identical to that of an especially intense magnetic field utilized to 2 aligned graphene sheets.
An article on the research has lately been revealed in Physical Review Letters and was chosen to function on the problem’s cowl. It may also be downloaded from the arXiv platform.
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 by means of a Young Investigator grant.
“I performed the analysis, and it was computationally verified by Lado,” Ramires advised. “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 should be shut sufficient collectively for the digital orbitals of 1 to work together with the digital orbitals of the opposite, she defined.
This means a separation as shut as roughly one angstrom (10-10 meter or zero.1 nanometer), which is the space between two carbon atoms in graphene.
Another requirement is a small angle of twist for every sheet in comparison with the opposite — lower than one diploma (α<1°).
Although totally theoretical (analytical and numerical), the research has clear technological potential, because it reveals versatile materials resembling graphene might be manipulated in hitherto unexplored regimes.
“The artificial magnetic fields proposed previously were based on the application of forces to deform the material. Our proposal enables the generation of these fields to be controlled with much greater precision. This could have practical applications,” Ramires stated.
The exotic states of matter induced by synthetic magnetic fields are related to the looks of “pseudo-Landau levels” in graphene sheets.
Landau ranges — named after the Soviet physicist and mathematician Lev Landau (1908-1968), Nobel Laureate in Physics in 1962 — are a quantum phenomenon whereby in the presence of a magnetic field, electrically charged particles can solely occupy orbits with discrete power values. The variety of electrons in every Landau stage is straight proportional to the magnitude of the utilized magnetic field.
“These states are well-located in space; when particles interact at these levels, the interactions are much more intense than usual. The formation of pseudo-Landau levels explains why artificial magnetic fields make exotic properties such as superconductivity or spin liquids appear in the material,” Ramires stated.