Unexpected Quantum Effects In Natural Double-Layer Graphene
An international research team led by the University of Göttingen has detected unique quantum effects in high-precision researches of natural double-layer graphene and has interpreted them together with the College of Texas at Dallas utilizing their academic work.
This research offers new insights into the interaction of the charge carriers and the different stages and contributes to the understanding of the procedures involved. The LMU in Munich and also the National Institute for Materials Science in Tsukuba, Japan, were also involved in the research. The outcomes were published in Nature.
The novel product graphene, a wafer-thin layer of carbon atoms, was first found by a British research group in 2004. Graphene is known for its extraordinarily huge electrical conductivity, among other unusual properties.
If two specific graphene layers are turned at an extremely specific angle to each other, the system even becomes superconducting (i.e., carries electricity without any resistance) and also exhibits other exciting quantum effects such as magnetism. Nevertheless, the production of such twisted graphene double-layers has so far required increased technical effort.
This unique study utilized the naturally occurring form of double-layer graphene, where no complex fabrication is needed. In a 1st step, the sample is isolated from a piece of graphite in the laboratory utilizing a simple adhesive tape. To see quantum mechanical effects, the Göttingen team then applied a high electric field perpendicular to the example: the electronic structure of the system changes, and a strong accumulation of charge carriers with similar energy occurs.
At temperatures just over absolute zero of minus 273.15 levels Celsius, the electrons in the graphene can interact with each other– and a variety of complex quantum stages emerge completely unexpectedly. For instance, the interactions cause the spins of the electrons to align, making the material magnetic without any additional external influence.
By changing the electric field, researchers could continuously change the strength of the interactions of the charge providers in the double-layer graphene. Under specific conditions, the electrons could be so restricted in their freedom of movement that they create their own electron lattice and can no more contribute to transporting charge due to their mutual repulsive interaction. The system is then electrically insulating.
“Future research could now focus on investigating further quantum states,” said Professor Thomas Weitz and Ph.D. student Anna Seiler, Faculty of Physics at Göttingen University.
“In order to access other applications, for example, unique computer systems such as quantum computers, researchers would need to find how these outcomes could be achieved at higher temperatures.However, a significant benefit of the existing system established in our new research lies in the simplicity of the fabrication of the materials.”
Reference:
Anna M. Seiler et al. Quantum cascade of correlated phases in trigonally warped bi-layergraphene. Nature 2022. Doi: 10.1038/s41586-022-04937-1. Text also available via preprint: https://arxiv.org/abs/2111.06413
Read the original article on The Quantum Insider.
