Graphene, a single layer of carbon atoms in a hexagonal lattice, has gained significant attention in the scientific community due to its unique electronic properties. However, when two or more layers of graphene are combined, new and exotic phenomena emerge. One such phenomenon is the formation of flat bands in twisted bilayer graphene, which can lead to correlated insulator behavior and superconductivity.
When two sheets of graphene are stacked on top of each other with a specific twist angle, a moiré pattern emerges, resulting in the formation of flat bands. These flat bands minimize the kinetic energy of electrons and enhance electron-electron interactions, leading to the emergence of strongly correlated electronic phenomena such as unconventional superconductivity.
Ching-Kai Chiu and Congcong Le, along with their team at RIKEN iTHEMS, have demonstrated that introducing a spatially varying magnetic field can further enhance the exotic properties of twisted bilayer graphene. The magnetic field gives rise to additional magic angles and flat bands that are quadruply degenerate, providing new opportunities for studying correlated phenomena.
The discovery of flat bands and correlated electron phenomena in twisted bilayer graphene has opened up new avenues for research in the field of condensed matter physics. Scientists are now exploring the possibility of finding other materials that exhibit similar properties in order to expand our understanding of exotic physics.
The engineering of flat bands in twisted graphene layers through the use of magnetic fields represents a significant advancement in the field of materials science. The exploration of these exotic properties has the potential to revolutionize the development of electronic devices with unprecedented functionalities beyond those of traditional silicon-based technologies. Further research in this area is crucial for unlocking the full potential of flat bands in graphene and their applications in future technologies.
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