arXiv subjects

L. Y. Gorelik

Publications and source records attributed to L. Y. Gorelik.

44 records · Page 3Linked to original sources

arXiv1998

Shuttle Instability in Self-Assembled Coulomb Blockade Nanostructures

We study a simple model of a self-assembled, room temperature Coulomb-blockade nanostructure containing a metallic nanocrystal or grain connected by soft molecular links to two metallic electrodes. Self-excitation of periodic grain vibrations at 10 - 100 GHz is shown to be possible for a sufficiently large bias voltage leading to a novel `shuttle mechanism' of discrete charge transfer and a current through the nanostructure proportional to the vibration frequency. For the case of weak electromechanical coupling an analytical approach is developed which together with Monte Carlo simulations shows that the shuttle instability for structures with high junction resistances leads to hysteresis in the current - voltage characteristics.

cond-mat.mes-hall↗

arXiv1998

Superconducting single-mode contact as a microwave-activated quantum interferometer

The dynamics of a superconducting quantum point contact biased at subgap voltages is shown to be strongly affected by a microwave electromagnetic field. Interference among a sequence of temporally localized, microwave-induced Landau-Zener transitions between current carrying Andreev levels results in energy absorption and in an increase of the subgap current by several orders of magnitude. The contact is an interferometer in the sense that the current is an oscillatory function of the inverse bias voltage. Possible applications to Andreev-level spectroscopy and microwave detection are discussed.

cond-mat.supr-con↗

arXiv1998

Shuttle Mechanism for Charge Transfer in Coulomb Blockade Nanostructures

Room-temperature Coulomb blockade of charge transport through composite nanostructures containing organic inter-links has recently been observed. A pronounced charging effect in combination with the softness of the molecular links implies that charge transfer gives rise to a significant deformation of these structures. For a simple model system containing one nanoscale metallic cluster connected by molecular links to two bulk metallic electrodes we show that self-excitation of periodic cluster oscillations in conjunction with sequential processes of cluster charging and decharging appears for a sufficiently large bias voltage. This new `electron shuttle' mechanism of discrete charge transfer gives rise to a current through the nanostructure, which is proportional to the cluster vibration frequency.

cond-mat↗

arXiv1997

Ordering effect of Coulomb interaction in ballistic double-ring systems

We study a model of two concentric onedimensional rings with incommensurate areas $A_1$ and $A_2$, in a constant magnetic field. The two rings are coupled by a nonhomogeneous inter-ring tunneling amplitude, which makes the one-particle spectrum chaotic. For noninteracting particles the energy of the many-body ground state and the first excited state exhibit random fluctuations characterized by the Wigner-Dyson statistics. In contrast, we show that the electron-electron interaction orders the magnetic field dependence of these quantities, forcing them to become periodic functions, with period $ \propto 1/(A_1 + A_2)$. In such a strongly correlated system the only possible source of disorder comes from charge fluctuations, which can be controlled by a tunable inter-ring gate voltage.

cond-mat.mes-hall↗

arXiv1997

Coulomb correlations and coherent charge tunneling in mesoscopic coupled rings

We study the effect of a strong electron-electron (e-e) interaction in a system of two concentric one-dimensional rings with incommensurate areas A_1 and A_2, coupled by a tunnel amplitude. For noninteracting particles the magnetic moment (persistent current) m of the many-body ground state and first excited states is an irregular function of the external magnetic field. In contrast, we show that when strong e-e interactions are present the magnetic field dependence of m becomes periodic. In such a strongly correlated system disorder can only be caused by inter-ring charge fluctuations, controllable by a gate voltage. The oscillation period of m is proportional to 1/(A_1 + A_2) if fluctuations are suppressed. Coherent inter-ring tunneling doubles the period when charge fluctuations are allowed.

cond-mat.mes-hall↗

arXiv1996

Spatial Structure in Mode Population Induced by Coherent Pumping in a Ballistic Quantum Channel

We predict a spatially varying mode population to appear in a GaAs/AlGaAs-2DEG ballistic quantum channel pumped by a THz-field. If a resonant coupling between two modes is suddenly switched on at the entrance, Rabi oscillations in the mode population will arise. We propose to use an array of gates in order to simulate a moving quantum point contact for detecting the mode population oscillations, since they discriminate between different modes. By consecutively activating them we expect to see both photovoltaic effects and photoconductive effects which can easily be distinguished from noise.

cond-mat↗

arXiv1995

MICROWAVE-INDUCED RESONANT REFLECTION AND LOCALIZATION OF BALLISTIC ELECTRONS IN QUANTUM MICROCHANNELS

We show that electron transport in a ballistic microchannel supporting both propagating and reflected modes can be completely blocked by applying a microwave electromagnetic field. The effect is due to resonant reflection caused by multiple coherent electron-photon scattering involving at least two spatially localized scattering centers in the channel. With many such scattering centers present the conductance is shown to have an irregular dependence on bias voltage, gate voltage and frequency with irregularily spaced dips corresponding to resonant reflection. When averaged over bias, gate voltage or frequency the conductance will decay exponentially with channel length in full analogy with the localization of 1D electrons caused by impurity scattering.

cond-mat↗

arXiv1995

MICROWAVE-INDUCED "SOMERSAULT EFFECT" IN FLOW OF JOSEPHSON CURRENT THROUGH A QUANTUM CONSTRICTION

We consider the supercurrent flow through gated mesoscopic semiconductor hetrostructures in which a two-dimensional normal constriction is confined between superconducting electrodes. We show that for these structures the Josephson current, carried by quantized electron modes, can be strongly affected by an electromagnetic field. Photon-assisted Landau-Zener transitions between Andreev bound states in the constriction manifest themselves in one of two ways: (i) If the phase difference between the superconducting elements is fixed a series of reversals in the direction of supercurrent flow occurs (Somersault effect). (ii) If instead the junction is current biased a series of voltage spikes is seen. Both manifestations are a direct consequence of the discrete energy spectrum of the mesoscopic junction. We discuss necessary conditions for the described phenomena to be experimentally observable.

cond-mat↗