Browsing by Author "Rees, D. G."

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Nonlinear transport of the inhomogeneous Wigner solid in a channel geometry
(2016-11-23)
Badrutdinov, A. O.
;
Smorodin, A. V.
;
Rees, D. G.
;
Lin, J. Y.
;
Konstantinov, D.
The transport properties of an electronic Wigner solid (WS) on the surface of superfluid helium-4 are investigated in a geometry that allows WS systems of significantly different sizes to be defined. We probe and compare transport phenomena attributed to the electronic order, such as Bragg-Cherenkov scattering and the WS sliding transition, in the cases of a long homogeneous WS, a small WS island, and a long inhomogeneous WS. We find no significant WS size effects on the transport properties, in contrast to predictions of theoretical works, which indicates an absence of long-range order in the WS systems under consideration. For the inhomogeneous WS, consisting of two distinct WSs connected in series, a complex interplay of individual WS transport properties is observed, as revealed in the observation of two separate Bragg-Cherenkov plateaus and WS sliding transitions. A simple model is proposed that provides a qualitative explanation of this behavior.
Stability of Surface State Electrons on Helium Films
(2016-05)
Leiderer, P.
;
Scheer, E.
;
Kono, K.
;
Lin, J. -J.
;
Rees, D. G.
Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the \'quantum melting\' of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degenerate regime on thin helium films and microstructured substrates, for which the surface instability is suppressed. We demonstrate that, although the electron densities obtained exceed those for bulk helium substrates, observation of quantum melting remains challenging. We discuss possible solutions to the technical challenges involved.
Stability of Surface State Electrons on Helium Films
(2016-05-01)
Leiderer, P.
;
Scheer, E.
;
Kono, K.
;
Lin, J. -J.
;
Rees, D. G.
Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the 'quantum melting' of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degenerate regime on thin helium films and microstructured substrates, for which the surface instability is suppressed. We demonstrate that, although the electron densities obtained exceed those for bulk helium substrates, observation of quantum melting remains challenging. We discuss possible solutions to the technical challenges involved.
Structural Transitions in a Quasi-1D Wigner Solid on Liquid Helium
(2016-01-01)
Beysengulov, N. R.
;
Rees, D. G.
;
Lysogorskiy, Yu.
;
Galiullin, N. K.
;
Vazjukov, A. S.
We present a detailed study of structural transitions of an electron system on liquid helium in quasi-1D confinement geometry. The structural transitions are experimentally observed as current oscillations in transport measurements with changing electrostatic confinement parameters. Finite element modelling and Monte Carlo simulations were used to investigate the electron configuration. With increasing electron density, the single chain of electrons splits into a two-, three- and so on row configuration. A proliferation of defects accompanies each structural transition. We find a good agreement between the observed current modulation and the evolution of the electron row configuration predicted by our calculations.
The Helium Field Effect Transistor (II): Gated Transport of Surface-State Electrons Through Micro-constrictions
(2016-11)
Shaban, F.
;
Ashari, M.
;
Lorenz, T.
;
Rau, R.
;
Scheer, E.
We present transport measurements of surface-state electrons on liquid helium films in confined geometry. The measurements are taken using split-gate devices similar to a field effect transistor. The number of electrons passing between the source and drain areas of the device can be precisely controlled by changing the length of the voltage pulse applied to the gate electrode. We find evidence that the effective driving potential depends on electron-electron interactions, as well as the electric field applied to the substrate. Our measurements indicate that the mobility of electrons on helium films can be high and that microfabricated transistor devices allow electron manipulation on length scales close to the interelectron separation. Our experiment is an important step toward investigations of surface-state electron properties at much higher densities, for which the quantum melting of the system to a degenerate Fermi gas should be observed.
Transport of Electrons on Liquid Helium in a Microchannel Device near the Current Threshold
(2016-09)
Beysengulov, N. R.
;
Rees, D. G.
;
Tayurskii, D. A.
;
Kono, K.
;
物理研究所
We study the transport of strongly interacting electrons on the surface of liquid helium confined in a microchannel geometry, near the current threshold point. The current threshold depends on the electrostatic confinement, created by the microchannel electrodes, and on the electrostatic potential of electron system. Depending on the geometry of the microchannel, the current pinch-off can occur at the center or move to the edges of the microchannel, as confirmed by Finite Element Model calculations. The confining potential dependence of electron conductivity above the current threshold point is consistent with a classical charge continuum model. However, we find that below the threshold point electron transport is suppressed due to charging energy effects.
Unidirectional Charge Transport via Ripplonic Polarons in a Three-Terminal Microchannel Device
(2020-03-23)
Badrutdinov, A. O.
;
Rees, D. G.
;
Lin, J. Y.
;
Smorodin, A., V
;
Konstantinov, D.
We study the transport of surface electrons on superfluid helium through a microchannel structure in which the charge flow splits into two branches, one flowing straight and one turned at 90 degrees. According to Ohm's law, an equal number of charges should flow into each branch. However, when the electrons are dressed by surface excitations (ripplons) to form polaronlike particles with sufficiently large effective mass, all the charge follows the straight path due to momentum conservation. This surface-wave induced transport is analogous to the motion of electrons coupled to surface acoustic waves in semiconductor 2DEGs.