Electron–electron interactions in high-mobility conductors can give rise to transport signatures resembling those described by classical hydrodynamics. Using a nanoscale scanning magnetometer, we imaged a distinctive hydrodynamic transport pattern—stationary current vortices—in a monolayer graphene device at room temperature. By measuring devices with increasing characteristic size, we observed the disappearance of the current vortex and thus verified a prediction of the hydrodynamic model. We further observed that vortex flow is present for both hole- and electron-dominated transport regimes but disappears in the ambipolar regime. We attribute this effect to a reduction of the vorticity diffusion length near charge neutrality. Our work showcases the power of local imaging techniques for unveiling exotic mesoscopic transport phenomena.
In 1988, it was proposed that there was quantum Hall effect without Landau levels. [3] This quantum Hall effect is referred to as the quantum anomalous Hall (QAH) effect. There is also a new concept of the quantum spin Hall effect which is an analogue of the quantum Hall effect, where spin currents flow instead of charge currents. [4]
How are spin currents and vorticity in electron vortices related?
"Observation of current whirlpools in graphene at room temperature" (2024) https://www.science.org/doi/10.1126/science.adj2167 :
Could this imaging capability help observe this known free electrons from graphene approach?
From "Physicists Build Circuit That Generates Clean, Limitless Power from Graphene (2020)" https://news.ycombinator.com/item?id=30825430#30839636 :
[Fractional] Quantum Hall Effect: https://news.ycombinator.com/item?id=39384522 :
How are spin currents and vorticity in electron vortices related?