arXiv subjects

Askhat K. Bakarov

Publications and source records attributed to Askhat K. Bakarov.

8 recordsLinked to original sources

arXiv2026

Transport Detection of Whirlpools in GaAs Electron Liquid

We report the formation of large-scale steady-state whirlpools in a GaAs-based two-dimensional electron liquid and demonstrate them by straightforward transport measurements. A whirlpool forming inside a circular cavity adjoining a wide conducting channel appears as a negative four-terminal resistance over a broad range of temperatures and cavity sizes. The effect scales with the Gurzhi length, in quantitative accord with the hydrodynamic analogy. Obtained results firmly establish this analogy and probe the limits of its applicability.

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arXiv2026

Electron Tesla valve

In solids, frequent electron-electron collisions can induce collective, fluid-like electron transport. While this regime offers a powerful framework for exploring many-body phenomena, there is still a lack in functional electronic device actively exploiting hydrodynamic behaviour of electrons. Here, we introduce a solid-state analogue of a Tesla valve $\unicode{x2013}$ a passive fluidic diode that rectifies flow without moving parts. Lithographically defined in high-mobility GaAs two-dimensional electron gas, the device exhibits abrupt rectification producing a more than tenfold difference between forward and reverse resistances. This threshold behaviour, reminiscent of the onset of turbulence in fluidic Tesla valves, points to the emergence of turbulent regime in the electron liquid $\unicode{x2013}$ a long-predicted, but yet unobserved state of electronic matter. More broadly, our work demonstrates the fruitfulness of the hydrodynamic analogy: fluidic technologies can be readily adopted to create novel electronic devices. Here, this is realized through a solid-state rectifier whose operation relies on a new physical mechanism, interparticle collisions.

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arXiv2026

Nanomechanical detection of vortices in an electron fluid

Electron vortices are the quintessential signature of a viscous electron fluid. For decades, their detection relied on indirect transport measurements with persistently debated interpretations. Recently, scanning magnetometry enabled direct visualization, yet these techniques demand considerable sophistication. Here we introduce a conceptually different and inherently simpler paradigm based on nanomechanics. By integrating a circular cavity into a suspended resonator, we create a vortex whose circulating current generates a magnetic moment. In an in-plane magnetic field, this moment experiences a torque, driving vibrations that directly reveal the vortex's presence and nature. We detect ballistic and hydrodynamic vortices and trace their temperature-driven crossover. Our work establishes nanomechanics as a platform for electron hydrodynamics, showing that viscosity - subtle in transport - is one of the dominant factors shaping nanoelectromechanical response.

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arXiv2025

Slip electron flow in GaAs microscale constrictions

Hydrodynamic electron transport in solids, governed by momentum-conserving electron-electron collisions, offers a unique framework to explore collective phenomena. Within this framework, correlated electron motion is modeled as viscous fluid flow, with viscosity serving as the interaction parameter. Advances in electron hydrodynamics remain constrained by two unresolved issues: the questionable existence of perfect boundary slip$\unicode{x2013}$a hallmark of frictionless transport$\unicode{x2013}$in electron fluids, and the lack of quantitative experimental confirmation of the theoretical relation linking the viscosity to electron-electron scattering length. Here, we resolve this through independent measurements of these quantities in the same electron system in GaAs/AlGaAs heterostructure. Our experiments provide direct evidence of perfect boundary slip in microscale constrictions$\unicode{x2013}$unprecedented phenomenon for electron liquid that parallels ultrafast water transport in carbon nanotubes. These findings bridge the fields of electron hydrodynamics and nanofluidics, highlighting the transformative potential of hydrodynamic engineering across condensed matter and fluidic technologies.

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arXiv2025

The role of small-angle electron-electron scattering in transverse magnetic focusing experiment

We demonstrate the crucial role of small-angle scattering in transverse magnetic focusing (TMF) in ballistic GaAs/AlGaAs heterostructures. Measurements in various samples show that the role significantly depends on their geometry. We propose a phenomenological model parameterizing this dependence with the angular acceptance of the detecting contact. This model is consistent with the diversity of experimental data and therefore enables accurate extraction of the key characteristic of inter-electron (e-e) interaction $\unicode{x2013}$ the e-e scattering length $\unicode{x2013}$ from TMF experiment, thus turning it into a uniquely effective tool for studying e-e scattering.

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arXiv2024

Electronic state back action on mechanical motion in a quantum point contact coupled to a nanomechanical resonator

In a nanomechanical resonator coupled to a quantum point contact, the back action of the electronic state on mechanical motion is studied. The quantum point contact conductance changing with subband index and the eigenfrequency of the resonator are found to correlate. A model is constructed explaining the frequency deviations by the alternating ability of the quantum point contact to screen the piezoelectric charge induced by mechanical oscillations. The observed effects can be used to develop electromechanical methods for studying the density of states in quasi-one-dimensional systems.

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arXiv2024

Temperature Dependence of Electron Viscosity in Superballistic GaAs Point Contacts

Electron transport in suspended and non-suspended GaAs point contacts (PCs) of different widths is experimentally studied. The superballistic contribution to the conductance, that demonstrates a distinctive quadratic dependence on the PC width and temperature growth, is extracted from the experiment. The studied PCs are shown to be described in the framework of hydrodynamic electron flow a in wide temperature range. At low temperatures, $T$, the viscosity is found out to obey the law $1/T^2$ expected for 2D systems, while at higher temperatures it has the dependence $1/T$. Similar measurements performed after the suspension of PCs, i.e. their separation from substrate, show that the electron viscosity reduces in the whole temperature range, that indicates an enhanced electron-electron interaction in suspended structures.

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arXiv2014

Resonant optical control of the electrically-induced spin polarization by periodic excitation

We show that the electron spin polarization generated by an electrical current may have its direction controlled and magnitude amplified by periodic optical excitation. The electrical and optical spin control methods were combined and implemented in a two-dimensional electron gas. By Kerr rotation in an external transverse magnetic field, we demonstrate unexpected long-lived coherent spin oscillations of the current-induced signal in a system with large spin-orbit interaction. Using a single linearly polarized pulse for spin manipulation and detection, we found a strong dependence on the pulse optical power and sample temperature indicating the relevance of the hole spin in the electron spin initialization. The signal was mapped in a Hall bar as function of the position relative to the injection contact. Finally, the presence of an in-plane spin polarization was directly verified by rotating the experimental geometry.

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