arXiv subjects

Valentin Yu. Kachorovskii

Publications and source records attributed to Valentin Yu. Kachorovskii.

3 recordsLinked to original sources

arXiv2022

Cyclotron- and magnetoplasmon resonances in bilayer graphene ratchets

We report on a tunable - by magnetic field and gate voltage - conversion of terahertz radiation into a dc current in spatially modulated bilayer graphene. We experimentally demonstrate that the underlying physics is related to the so-called ratchet effect. Our key findings are the direct observation of a sharp cyclotron resonance in the photocurrent and the demonstration of two effects caused by electron-electron interaction: the plasmonic splitting of the resonance due to long-range Coulomb coupling and the partial suppression of its second harmonic due to fast interparticle collisions. We develop a theory which perfectly fits our data. We argue that the ratchet current is generated in the hydrodynamic regime of non-ideal electron liquid.

cond-mat.mes-hall↗

arXiv2021

Ratchet effect in spatially modulated bilayer graphene: Signature of hydrodynamic transport

We report on the observation of the ratchet effect -- generation of direct electric current in response to external terahertz (THz) radiation -- in bilayer graphene, where inversion symmetry is broken by an asymmetric dual-grating gate potential. As a central result, we demonstrate that at high temperature, $T = 150~\textrm{K}$, the ratchet current decreases at high frequencies as $ \propto 1/ω^2$, while at low temperature, $T = 4.2~\textrm{K}$, the frequency dependence becomes much stronger $\propto 1/ω^6$. The developed theory shows that the frequency dependence of the ratchet current is very sensitive to the ratio of the electron-impurity and electron-electron scattering rates. The theory predicts that the dependence $1/ω^6$ is realized in the hydrodynamic regime, when electron-electron scattering dominates, while $1/ω^2$ is specific for the drift-diffusion approximation. Therefore, our experimental observation of a very strong frequency dependence reveals the emergence of the hydrodynamic regime.

cond-mat.mes-hall↗

arXiv1998

Quantum conductivity corrections in two dimensional long-range disordered systems with strong spin-orbit splitting of electron spectrum

We study quantum corrections to conductivity in a 2D system with a smooth random potential and strong spin-orbit splitting of the spectrum. We show that the interference correction is positive and down to the very low temperature can exceed the negative correction related to electron-electron interactions. We discuss this result in the context of the problem of the metal-insulator transition in Si-MOSFET structures.

cond-mat.mes-hall↗