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We consider quantum transport and tunneling magnetoresistance (TMR) through an interacting quantum dot in the Coulomb blockade regime, attached to ferromagnetic leads. We show that there exist two kinds of anomalies of TMR, which have…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Piotr Stefanski

Artificial molecules containing just one or two electrons provide a powerful platform for studies of orbital and spin quantum dynamics in nanoscale devices. A well-known example of these dynamics is tunneling of electrons between two…

Within a phonon-assisted resonance level model we develop a self-consistent procedure for calculating electron transport currents in molecular junctions with intermediate to strong electron-phonon interaction. The scheme takes into account…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Michael Galperin , Abraham Nitzan , Mark A. Ratner

We consider a quantum dot attached to leads in the Coulomb blockade regime which has a spin 1/2 ground state. We show that by applying an ESR field to the dot-spin the stationary current in the sequential tunneling regime exhibits a…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Hans-Andreas Engel , Daniel Loss

Resonant tunneling of electrons between two ferromagnets and a quantum dot in the presence of an externally applied magnetic field reveals a strong gate dependence in the linear and nonlinear bias regime. This gate dependence originates…

Mesoscale and Nanoscale Physics · Physics 2020-07-08 S. Mundinar , A. Hucht , J. König , S. Weiss

A multi-level Anderson model is employed to simulate the system of a nanostructure tunnel junction with any number of one-particle energy levels. The tunneling current, including both shell-tunneling and shell-filling cases, is…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 David M. -T. Kuo , Yia-Chung Chang

Magneto-transport properties in closed and open loop structures are carefully reviewed within a tight-binding formalism. A novel mesoscopic phenomenon where a non-vanishing current is observed in a conducting loop upon the application of an…

Mesoscale and Nanoscale Physics · Physics 2015-08-13 Paramita Dutta , Santanu K. Maiti

Coherent spin-dependent electronic transport is investigated in a molecular junction made of polymeric chain attached to ferromagnetic electrodes (Ni and Co, respectively). Molecular system is described by a simple Huckel model, while the…

Soft Condensed Matter · Physics 2007-05-23 Kamil Walczak

We have developed a quantitative theory of resonant tunneling of magnetic flux between discrete macroscopically distinct quantum states in SQUID systems. The theory is based on the standard density-matrix approach. Its new elements include…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 D. V. Averin , Jonathan R. Friedman , J. E. Lukens

We report the observation of two fundamental sub-gap transport processes through a quantum dot (QD) with a superconducting contact. The device consists of a carbon nanotube contacted by a Nb superconducting and a normal metal contact.…

Mesoscale and Nanoscale Physics · Physics 2015-11-30 J. Gramich , A. Baumgartner , C. Schönenberger

We show that an instability may be present in resonant tunneling through a quantum well in one, two and three dimensions, when the resonance lies near the emitter Fermi level. A simple semiclassical model which simulates the resonance and…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 G. Obermair , J. Inkoferer , F. Claro

We study theoretically the transmission through a quantum dot molecule embedded in the arms of an Aharonov-Bohm four quantum dot ring threaded by a magnetic flux. The tunable molecular coupling provides a transmission pathway between the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 Daniel A. Lovey , Sergio S. Gomez , Rodolfo H. Romero

Tunneling of a two-state particle through a squeezed vacuum is considered. It has been shown that repetitive measurement or interaction with the external field can preserve the coherence. Moreover, the coherence time in terms of the…

Quantum Physics · Physics 2015-06-18 Samyadeb Bhattacharya , Sisir Roy

The coherent spin dependent transport through a set of two capacitively coupled quantum dots placed in a magnetic field is considered within the equation of motion method. The magnetic field breaks the spin degeneracy. For special choices…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 S. Lipinski , D. Krychowski

We calculate the ensemble averaged persistent current on disordered mesoscopic rings with an embedded quantum dot. We model the quantum dot as a single resonance and use Random Matrix Theory to model the impurities in the ring. Using…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 E. H. Martins Ferreira , M. C. Nemes , H. A. Weidenmueller

We investigate the dynamics of two interacting electrons confined to a pair of coupled quantum dots driven by an external AC field. By numerically integrating the two-electron Schroedinger equation in time, we find that for certain values…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 C. E. Creffield , G. Platero

We study the noise of the cotunneling current through one or several tunnel-coupled quantum dots in the Coulomb blockade regime. The various regimes of weak and strong, elastic and inelastic cotunneling are analyzed for quantum-dot systems…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Eugene Sukhorukov , Guido Burkard , Daniel Loss

We consider an Aharonov-Bohm interferometer, connected to two electronic reservoirs, with a quantum dot embedded on one of its arms. We find a general expression for the persistent current at steady state, valid for the case where the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 O. Entin-Wohlman , Y. Imry , A. Aharony

The electron tunneling through a molecular junction modeled by a single site weakly coupled to two leads is studied in the presence of a time-dependent external field using a master equation approach. In the case of small bias voltages and…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Guangqi Li , Michael Schreiber , Ulrich Kleinekathoefer

Quantum particles can penetrate potential barriers by tunneling (1). If that barrier is rotating, the tunneling process is modified (2,3). This is typical for electrons in atoms, molecules or solids exposed to strong circularly polarized…