We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)-a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.
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http://dx.doi.org/10.1103/PhysRevLett.116.196801 | DOI Listing |
Phys Rev Lett
November 2024
Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
We report on the observation of Coulomb drag between graphene-hexagonal boron nitride (h-BN) moiré heterostructure with a moiré wavelength of ∼14 nm and an intrinsic graphene with a lattice constant of ∼0.25 nm. By tuning carrier densities of each graphene layer independently, we find that charge carriers in moiré minibands, i.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Physics and Astronomy, University of Manchester, Manchester, UK.
Coulomb drag between adjacent electron and hole gases has attracted considerable attention, being studied in various two-dimensional systems, including semiconductor and graphene heterostructures. Here we report measurements of electron-hole drag in the Planckian plasma that develops in monolayer graphene in the vicinity of its Dirac point above liquid-nitrogen temperatures. The frequent electron-hole scattering forces minority carriers to move against the applied electric field due to the drag induced by majority carriers.
View Article and Find Full Text PDFSci Rep
October 2024
Abrikosov Center for Theoretical Physics, MIPT, Dolgoprudnyi, Moscow Region, Russia, 141701.
We study the effect of Coulomb drag between graphene layers in presence of viscosity term. To do this, we use the simple model of Stokes equations for drift velocities in active and passive layers, known as Pogrebinskii's approach. The solution to these equations allows us to find the potential distribution, and thus the non-local drag resistance of passive layer.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
October 2024
Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz 55128, Germany.
Hydraulic energy is a key component of the global energy mix, yet there exists no practical way of harvesting it at small scales, from flows with low Reynolds number. This has triggered a search for alternative hydroelectric conversion methodologies, leading to unconventional proposals based on droplet triboelectricity, water evaporation, osmotic energy, or flow-induced ionic Coulomb drag. Yet, these approaches systematically rely on ions as intermediate charge carriers, limiting the achievable power density.
View Article and Find Full Text PDFNat Commun
October 2024
Department of Biomedical Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Institute of Innovative Materials, Southern University of Science and Technology, Shenzhen, P.R. China.
A sufficiently high current output of nano energy harvesting devices is highly desired in practical applications, while still a challenge. Theoretical evidence has demonstrated that Coulomb drag based on the ion-electron coupling interaction, can amplify current in nanofluidic energy generation systems, resulting in enhanced energy harvesting. However, experimental validation of this concept is still lacking.
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