AI Article Synopsis
- The study focuses on the quantum Hall effect in two graphene layers that are slightly misaligned (rotated by 2°) and highlights how varying the tunneling strength between the layers affects their behavior.
- A surprising observation of odd-integer quantum Hall physics occurs under conditions where this behavior isn't expected, suggesting complex interactions between the layers.
- The research also discusses how changes in electron density lead to transitions between different states, including interlayer coherence and a loss of coherence with increased density due to enhanced tunneling.
Article Abstract
We report on the quantum Hall effect in two stacked graphene layers rotated by 2°. The tunneling strength among the layers can be varied from very weak to strong via the mechanism of magnetic breakdown when tuning the density. Odd-integer quantum Hall physics is not anticipated in the regime of suppressed tunneling for balanced layer densities, yet it is observed. We interpret this as a signature of Coulomb interaction induced interlayer coherence and Bose-Einstein condensation of excitons that form at half filling of each layer. A density imbalance gives rise to reentrant behavior due to a phase transition from the interlayer coherent state to incompressible behavior caused by simultaneous condensation of both layers in different quantum Hall states. With increasing overall density, magnetic breakdown gains the upper hand. As a consequence of the enhanced interlayer tunneling, the interlayer coherent state and the phase transition vanish.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8289309 | PMC |
| http://dx.doi.org/10.1021/acs.nanolett.1c00360 | DOI Listing |
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