Lev Mourokh - Profile on Academia.edu (original) (raw)
Papers by Lev Mourokh
Temperature dependence of conductance of a tunnel junction coupled to a nanomechanical oscillator
We have analyzed the electric current through a tunnel junction having its transition matrix elem... more We have analyzed the electric current through a tunnel junction having its transition matrix elements modulated by a vibrational motion, with arbitrary voltage applied to the junction and arbitrary temperature of electrons in leads. This modulation can be realized by the introduction of molecules embedded between the leads, or by coupling the tunnel junction to a mechanical oscillator (cantilever). We find that the nonlinear current through this nanoelectromechanical system is proportional to the exponent of the ratio of the nonequilibrium dispersion of fluctuations of oscillator position and the tunneling length. An explicit expression for this dispersion of fluctuations is determined here on a microscopic basis, with its voltage and temperature dependencies. We have shown that for appropriate parameter values (oscillator mass and characteristic frequency, as well as the applied voltage bias) the conductance of the tunnel junction exhibits strong (almost exponential) dependence on temperature, which is in agreement with recent experimental data.
Journal of Chemical Physics, Jun 18, 2009
We propose a simple model of cytochrome c oxidase, including four redox centers and four protonab... more We propose a simple model of cytochrome c oxidase, including four redox centers and four protonable sites, to study the time evolution of electrostatically coupled electron and proton transfers initiated by the injection of a single electron into the enzyme. We derive a system of master equations for electron and proton state probabilities and show that an efficient pumping of protons across the membrane can be obtained for a reasonable set of parameters. All four experimentally observed kinetic phases appear naturally from our model. We also calculate the dependence of the pumping efficiency on the transmembrane voltage at different temperatures and discuss a possible mechanism of the redox-driven proton translocation.
Journal of Applied Physics, Jan 15, 2002
Electron Transport and Magnetic Response of a Double-Wire System
APS March Meeting Abstracts, Mar 1, 2002
Formation of electric field domains in a one-dimensional superlattice
APS, Mar 1, 2001
Transport and Nonequilibrium Fluctuatuions in Nanoelectromechanical Systems
APS, Mar 1, 2003
We analyze the dynamics of a nanomechanical oscillator coupled to an electrical tunnel junction w... more We analyze the dynamics of a nanomechanical oscillator coupled to an electrical tunnel junction with an arbitrary voltage applied across the junction and arbitrary temperature of electrons in the leads. We obtain explicit expressions for the fluctuations of oscillator position, its damping/decoherence rate, and the current through the structure. It is shown that quantum heating of the oscillator results in nonlinearity of the current-voltage characteristics. The effects of mechanical vacuum fluctuations are also discussed.
arXiv (Cornell University), Jul 20, 2007
We propose using semiconductor quantum dots for a simulation of chemical reactions as electrons a... more We propose using semiconductor quantum dots for a simulation of chemical reactions as electrons are redistributed among such artificial atoms. We show that it is possible to achieve various reaction regimes and obtain different reaction products by varying the speed of voltage changes applied to the gates forming quantum dots. Considering the simplest possible reaction, H 2 + H → H + H 2 , we show how the necessary initial state can be obtained and what voltage pulses should be applied to achieve a desirable final product. Our calculations have been performed using the Pechukas gas approach, which can be extended for more complicated reactions.
Terahertz-wave (1.4 THz) detection in quantum point contacts
Applied Physics Letters, Mar 1, 2008
Quantum Point Contacts: A Naturally-Formed Single-Spin System
Nature, Mar 1, 2007
Nonequilibrium Green’s Function Analysis of Induced Magnetic Moment in a Biased Double-Wire System
The induced magnetic moment of a semiconductor tunnel-coupled double quantum wire system is analy... more The induced magnetic moment of a semiconductor tunnel-coupled double quantum wire system is analyzed in the case when the parallel wires are connected to leads in a series arrangement, with their length perpendicular to the lead-to-lead current. We derive and solve the equations of motion for the double-wire electron Green's functions using the transfer-tunneling Hamiltonian formalism. This generalizes the Meir-Wingreen approach to structures having a continuous spectrum. The solution is employed to determine the average magnetic moment of the double-wire system induced by a magnetic field applied perpendicular to the plane of the wires and leads. We show that, at low temperature, the magnetic response of such a system can be either diamagnetic or paramagnetic depending on the applied bias and the equilibrium chemical potential of the leads. These properties of the double-wire structure introduce a mechanism for the lead-to-lead bias control of the induced magnetic moment of this system.
Reorganization energy in electron transport through semiconductor quantum dots
European Physical Journal-special Topics, Apr 12, 2021
The concept of reorganization energy is well established for molecular systems where the electron... more The concept of reorganization energy is well established for molecular systems where the electron transfer from a donor to an acceptor is accompanied by the reorganization of environment. It is not the case for bulk semiconductors with translational symmetry. However, in the presence of additional confinement, like in the quantum dots, the electron–phonon interaction is modified. We show that when the dots are not identical, the phonon reorganization energy can be determined. We calculate it for a realistic case of GaAs quantum dots.
The temperature dependence of the electron mobility in semiconductor quantum wires: fluctuation effects
Journal of Physics: Condensed Matter, Oct 6, 1997
Electron transport in semiconductor quantum wires with parabolic confined potentials is considere... more Electron transport in semiconductor quantum wires with parabolic confined potentials is considered. Non-Markovian Langevin-like equations are derived. A correspondence between the equations obtained and the balance equations for the non-equilibrium steady state is recognized. It is shown that at high temperature the electron mobility remains almost unchanged with increasing temperature. This is due to thermal fluctuations which affect the energy-loss rate via electron-phonon scattering.
Journal of Physics: Condensed Matter, May 25, 2011
We present two models for electron-driven uphill proton transport across lipid membranes, with th... more We present two models for electron-driven uphill proton transport across lipid membranes, with the electron energy converted to the proton gradient via the electrostatic interaction. In the first model, associated with the cytochrome c oxidase complex in the inner mitochondria membranes, the electrostatic coupling to the site occupied by an electron lowers the energy level of the protonbinding site, making the proton transfer possible. In the second model, roughly describing the redox loop in a nitrate respiration of E. coli bacteria, an electron displaces a proton from the negative side of the membrane to a shuttle, which subsequently diffuses across the membrane and unloads the proton to its positive side. We show that both models can be described by the same approach, which can be significantly simplified if the system is separated into several clusters, with strong Coulomb interaction inside each cluster and weak transfer couplings between them. We derive and solve the equations of motion for the electron and proton creation/annihilation operators, taking into account the appropriate Coulomb terms, tunnel couplings, and the interaction with the environment. For the second model, these equations of motion are solved jointly with a Langevintype equation for the shuttle position. We obtain expressions for the electron and proton currents and determine their dependence on the electron and proton voltage build-ups, on-site charging energies, reorganization energies, temperature, and other system parameters. We show that the quantum yield in our models can be up to 100% and the power-conversion efficiency can reach 35%.
Electron transport through Mn-O-Mn junction
APS March Meeting Abstracts, Mar 1, 2004
ABSTRACT
Diffusion and Localization in a One-Dimensional Superlattice with a Phonon Bath
APS, Mar 1, 2000
arXiv (Cornell University), Apr 2, 2015
We examine charge transport through a system of three sites connected in series in the situation ... more We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the site's energy decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.
MRS Proceedings, 2001
InGaN/GaN/AlGaN multiple quantum well light emitting diodes (MWQ LED's) with different levels of ... more InGaN/GaN/AlGaN multiple quantum well light emitting diodes (MWQ LED's) with different levels of p-doping in the contact layer have been characterized using surface photovoltage spectroscopy (SPS). Due to the high sensitivity of the SPS technique to the electric field, there is a strong correlation between the p-doping level in the contact layer and the magnitude of the SPS signal originating from the MQW region. The experimental results are confirmed by a numerical simulation. E4.2.1
![Research paper thumbnail of Erratum: Acoustically Induced Giant Synthetic Hall Voltages in Graphene [Phys. Rev. Lett. <b>128</b> , 256601 (2022)]](https://attachments.academia-assets.com/120688270/thumbnails/1.jpg)
](Physical Review Letters, Aug 31, 2022
After the publication of the Letter, we became aware of related work simultaneously published by ... more After the publication of the Letter, we became aware of related work simultaneously published by Bhalla et al. [Phys. Rev. B 105, 125407 (2022)]. Using Kubo's formalism, the authors theoretically studied "acoustogalvanic effects" in two-dimensional Dirac materials that arise from sound-induced pseudogauge fields. Despite the differences between our two models, the authors predicted acoustoelectric responses that qualitatively resemble our experimental observations.
Materials Sciences and Applications, 2018
Main design principles of the potent rylene-based class of dielectrophores are established in the... more Main design principles of the potent rylene-based class of dielectrophores are established in the present article. The proposed class of dielectrophores comprises polarizable aromatic core, conjugated with aromatic subunits, and bears resistive groups on the periphery. The aromatic subunits might comprise donor and acceptor groups for the desired level of polarizability of the molecule. Appropriate positions for donor and acceptor groups are established by quantum chemistry modeling. The design principles are demonstrated on the molecular design of an efficient rylene-based dielectrophore.
Photoreflectance characterization of an AlInAs/GaInAs heterojunction bipolar transistor structure with a chirped superlattice
Journal of Applied Physics, Feb 15, 2001
We have measured the photoreflectance spectrum at 300 K from an AlInAs/GaInAs (lattice matched to... more We have measured the photoreflectance spectrum at 300 K from an AlInAs/GaInAs (lattice matched to InP) heterojunction bipolar transistor structure with a chirped superlattice (ChSl) grown by molecular-beam epitaxy. From the observed Franz–Keldysh oscillations we have evaluated the built-in dc electric fields and associated doping levels in the n-GaInAs collector and n-AlInAs emitter regions. The oscillatory signal originating from the ChSl is caused both by the uniform quasielectric and nonuniform space-charge fields in this region.
Temperature dependence of conductance of a tunnel junction coupled to a nanomechanical oscillator
We have analyzed the electric current through a tunnel junction having its transition matrix elem... more We have analyzed the electric current through a tunnel junction having its transition matrix elements modulated by a vibrational motion, with arbitrary voltage applied to the junction and arbitrary temperature of electrons in leads. This modulation can be realized by the introduction of molecules embedded between the leads, or by coupling the tunnel junction to a mechanical oscillator (cantilever). We find that the nonlinear current through this nanoelectromechanical system is proportional to the exponent of the ratio of the nonequilibrium dispersion of fluctuations of oscillator position and the tunneling length. An explicit expression for this dispersion of fluctuations is determined here on a microscopic basis, with its voltage and temperature dependencies. We have shown that for appropriate parameter values (oscillator mass and characteristic frequency, as well as the applied voltage bias) the conductance of the tunnel junction exhibits strong (almost exponential) dependence on temperature, which is in agreement with recent experimental data.
Journal of Chemical Physics, Jun 18, 2009
We propose a simple model of cytochrome c oxidase, including four redox centers and four protonab... more We propose a simple model of cytochrome c oxidase, including four redox centers and four protonable sites, to study the time evolution of electrostatically coupled electron and proton transfers initiated by the injection of a single electron into the enzyme. We derive a system of master equations for electron and proton state probabilities and show that an efficient pumping of protons across the membrane can be obtained for a reasonable set of parameters. All four experimentally observed kinetic phases appear naturally from our model. We also calculate the dependence of the pumping efficiency on the transmembrane voltage at different temperatures and discuss a possible mechanism of the redox-driven proton translocation.
Journal of Applied Physics, Jan 15, 2002
Electron Transport and Magnetic Response of a Double-Wire System
APS March Meeting Abstracts, Mar 1, 2002
Formation of electric field domains in a one-dimensional superlattice
APS, Mar 1, 2001
Transport and Nonequilibrium Fluctuatuions in Nanoelectromechanical Systems
APS, Mar 1, 2003
We analyze the dynamics of a nanomechanical oscillator coupled to an electrical tunnel junction w... more We analyze the dynamics of a nanomechanical oscillator coupled to an electrical tunnel junction with an arbitrary voltage applied across the junction and arbitrary temperature of electrons in the leads. We obtain explicit expressions for the fluctuations of oscillator position, its damping/decoherence rate, and the current through the structure. It is shown that quantum heating of the oscillator results in nonlinearity of the current-voltage characteristics. The effects of mechanical vacuum fluctuations are also discussed.
arXiv (Cornell University), Jul 20, 2007
We propose using semiconductor quantum dots for a simulation of chemical reactions as electrons a... more We propose using semiconductor quantum dots for a simulation of chemical reactions as electrons are redistributed among such artificial atoms. We show that it is possible to achieve various reaction regimes and obtain different reaction products by varying the speed of voltage changes applied to the gates forming quantum dots. Considering the simplest possible reaction, H 2 + H → H + H 2 , we show how the necessary initial state can be obtained and what voltage pulses should be applied to achieve a desirable final product. Our calculations have been performed using the Pechukas gas approach, which can be extended for more complicated reactions.
Terahertz-wave (1.4 THz) detection in quantum point contacts
Applied Physics Letters, Mar 1, 2008
Quantum Point Contacts: A Naturally-Formed Single-Spin System
Nature, Mar 1, 2007
Nonequilibrium Green’s Function Analysis of Induced Magnetic Moment in a Biased Double-Wire System
The induced magnetic moment of a semiconductor tunnel-coupled double quantum wire system is analy... more The induced magnetic moment of a semiconductor tunnel-coupled double quantum wire system is analyzed in the case when the parallel wires are connected to leads in a series arrangement, with their length perpendicular to the lead-to-lead current. We derive and solve the equations of motion for the double-wire electron Green's functions using the transfer-tunneling Hamiltonian formalism. This generalizes the Meir-Wingreen approach to structures having a continuous spectrum. The solution is employed to determine the average magnetic moment of the double-wire system induced by a magnetic field applied perpendicular to the plane of the wires and leads. We show that, at low temperature, the magnetic response of such a system can be either diamagnetic or paramagnetic depending on the applied bias and the equilibrium chemical potential of the leads. These properties of the double-wire structure introduce a mechanism for the lead-to-lead bias control of the induced magnetic moment of this system.
Reorganization energy in electron transport through semiconductor quantum dots
European Physical Journal-special Topics, Apr 12, 2021
The concept of reorganization energy is well established for molecular systems where the electron... more The concept of reorganization energy is well established for molecular systems where the electron transfer from a donor to an acceptor is accompanied by the reorganization of environment. It is not the case for bulk semiconductors with translational symmetry. However, in the presence of additional confinement, like in the quantum dots, the electron–phonon interaction is modified. We show that when the dots are not identical, the phonon reorganization energy can be determined. We calculate it for a realistic case of GaAs quantum dots.
The temperature dependence of the electron mobility in semiconductor quantum wires: fluctuation effects
Journal of Physics: Condensed Matter, Oct 6, 1997
Electron transport in semiconductor quantum wires with parabolic confined potentials is considere... more Electron transport in semiconductor quantum wires with parabolic confined potentials is considered. Non-Markovian Langevin-like equations are derived. A correspondence between the equations obtained and the balance equations for the non-equilibrium steady state is recognized. It is shown that at high temperature the electron mobility remains almost unchanged with increasing temperature. This is due to thermal fluctuations which affect the energy-loss rate via electron-phonon scattering.
Journal of Physics: Condensed Matter, May 25, 2011
We present two models for electron-driven uphill proton transport across lipid membranes, with th... more We present two models for electron-driven uphill proton transport across lipid membranes, with the electron energy converted to the proton gradient via the electrostatic interaction. In the first model, associated with the cytochrome c oxidase complex in the inner mitochondria membranes, the electrostatic coupling to the site occupied by an electron lowers the energy level of the protonbinding site, making the proton transfer possible. In the second model, roughly describing the redox loop in a nitrate respiration of E. coli bacteria, an electron displaces a proton from the negative side of the membrane to a shuttle, which subsequently diffuses across the membrane and unloads the proton to its positive side. We show that both models can be described by the same approach, which can be significantly simplified if the system is separated into several clusters, with strong Coulomb interaction inside each cluster and weak transfer couplings between them. We derive and solve the equations of motion for the electron and proton creation/annihilation operators, taking into account the appropriate Coulomb terms, tunnel couplings, and the interaction with the environment. For the second model, these equations of motion are solved jointly with a Langevintype equation for the shuttle position. We obtain expressions for the electron and proton currents and determine their dependence on the electron and proton voltage build-ups, on-site charging energies, reorganization energies, temperature, and other system parameters. We show that the quantum yield in our models can be up to 100% and the power-conversion efficiency can reach 35%.
Electron transport through Mn-O-Mn junction
APS March Meeting Abstracts, Mar 1, 2004
ABSTRACT
Diffusion and Localization in a One-Dimensional Superlattice with a Phonon Bath
APS, Mar 1, 2000
arXiv (Cornell University), Apr 2, 2015
We examine charge transport through a system of three sites connected in series in the situation ... more We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the site's energy decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.
MRS Proceedings, 2001
InGaN/GaN/AlGaN multiple quantum well light emitting diodes (MWQ LED's) with different levels of ... more InGaN/GaN/AlGaN multiple quantum well light emitting diodes (MWQ LED's) with different levels of p-doping in the contact layer have been characterized using surface photovoltage spectroscopy (SPS). Due to the high sensitivity of the SPS technique to the electric field, there is a strong correlation between the p-doping level in the contact layer and the magnitude of the SPS signal originating from the MQW region. The experimental results are confirmed by a numerical simulation. E4.2.1
Physical Review Letters, Aug 31, 2022
After the publication of the Letter, we became aware of related work simultaneously published by ... more After the publication of the Letter, we became aware of related work simultaneously published by Bhalla et al. [Phys. Rev. B 105, 125407 (2022)]. Using Kubo's formalism, the authors theoretically studied "acoustogalvanic effects" in two-dimensional Dirac materials that arise from sound-induced pseudogauge fields. Despite the differences between our two models, the authors predicted acoustoelectric responses that qualitatively resemble our experimental observations.
Materials Sciences and Applications, 2018
Main design principles of the potent rylene-based class of dielectrophores are established in the... more Main design principles of the potent rylene-based class of dielectrophores are established in the present article. The proposed class of dielectrophores comprises polarizable aromatic core, conjugated with aromatic subunits, and bears resistive groups on the periphery. The aromatic subunits might comprise donor and acceptor groups for the desired level of polarizability of the molecule. Appropriate positions for donor and acceptor groups are established by quantum chemistry modeling. The design principles are demonstrated on the molecular design of an efficient rylene-based dielectrophore.
Photoreflectance characterization of an AlInAs/GaInAs heterojunction bipolar transistor structure with a chirped superlattice
Journal of Applied Physics, Feb 15, 2001
We have measured the photoreflectance spectrum at 300 K from an AlInAs/GaInAs (lattice matched to... more We have measured the photoreflectance spectrum at 300 K from an AlInAs/GaInAs (lattice matched to InP) heterojunction bipolar transistor structure with a chirped superlattice (ChSl) grown by molecular-beam epitaxy. From the observed Franz–Keldysh oscillations we have evaluated the built-in dc electric fields and associated doping levels in the n-GaInAs collector and n-AlInAs emitter regions. The oscillatory signal originating from the ChSl is caused both by the uniform quasielectric and nonuniform space-charge fields in this region.