Researchers have discovered that by introducing an alternating magnetic field to layers of twisted graphene, they can create even more exotic and intriguing properties, paving the way for groundbreaking advancements in electronic devices and materials science.
Demystifying Twisted Graphene
There are few things as close to a wonder material as graphene, which is a single layer of carbon atoms arranged in a hexagonal lattice. It has promised to enable exciting new, fundamentally different devices never before thought possible; its exotic electronic states — electrons move through it as if they are massless — have captured the imagination of both scientists and engineers.
The real fun, however, comes when we look into twisted graphene. So if we take two (or more) layers of graphene and lay them on top of one another, with a small twist between the planes, an enthralling pattern arises—the moiré pattern. This complex organization underpins a striking modification of the material’s properties, with possible behaviors spanning from correlated insulation to superconductivity, all depending on an exact twist angle.
A New Frontier Through Magnetism
Now, researchers at the interdisciplinary theoretical and mathematical sciences (iTHEMS) program of RIKEN have gone a step further in probing what might happen to the electrons in twisted bilayer graphene by adding an alternating magnetic field. Their new research, which appears in Physical Review Letters, shows that adding an extra magnetic element can induce even more exotic and surprising properties.
The secret is how the magnetic field couples to flat bands in twisted bilayer graphene. At some twist angles, the kinetic energy of electrons forms these flat bands, andit is at these ‘magic’ angles that the interactions between electrons take over. This can, in its turn, induce a multitude of highly correlated electronic states associated with unconventional superconductivity.
They have demonstrated that new magic angles and flat bands can be induced using a spatially alternating magnetic field, at quadruple (four-fold) degenerate points. Such a higher order of degeneracy hints at the presence of correlated phenomena that could be much more elaborate and interesting, providing a novel area for research.
Conclusion
In twisted graphene layers, this finding reveals a new class of exotic properties that are induced by the application of magnetic field as well as an important step toward the realization of topological superconductors in materials science and condensed matter physics. Through opening alternative paths by which to control and modulate the electronic behavior of this extraordinary material, scientists are enabling a new era of electronic devices for advanced electronics and uncharted realms of quantum physics. The hunt for new materials and technologies is about to carry on, while the twisted graphene and its magnetic chore will continue casting an enchanting hex upon scientists seeking novel effects across the world.
