J.-Q. Liang

Photon-assisted electron transmission resonance through a quantum well with spin-orbit coupling

Using the effective-mass approximation and Floquet theory, we study the electron transmission over a quantum well in semiconductor heterostructures with Dresselhaus spin-orbit coupling and an applied oscillation field. It is demonstrated by the numerical evaluations that Dresselhaus spin-orbit coupling eliminates the spin degeneracy and leads to the splitting of asymmetric Fano-type resonance peaks in the conductivity. In turn, the splitting of Fano-type resonance induces the spin-polarization-dependent electron current. The location and line shape of Fano-type resonance can be controlled by adjusting the oscillation frequency and the amplitude of the external field as well. These interesting features may be a very useful basis for devising tunable spin filters.

Effect of finite Coulomb interaction on full counting statistics of electronic transport through single-molecule magnet

Abstract We study the full counting statistics (FCS) in a single-molecule magnet (SMM) with finite Coulomb interaction U. For finite U the FCS, differing from U → ∞ , shows a symmetric gate-voltage-dependence when the coupling strengths with two electrodes are interchanged, which can be observed experimentally just by reversing the bias-voltage. Moreover, we find that the effect of finite U on shot noise depends on the internal level structure of the SMM and the coupling asymmetry of the SMM with two electrodes as well. When the coupling of the SMM with the incident-electrode is stronger than that with the outgoing-electrode, the super-Poissonian shot noise in the sequential tunneling regime appears under relatively small gate-voltage and relatively large finite U, and dose not for U → ∞ ; while it occurs at relatively large gate-voltage for the opposite coupling case. The formation mechanism of super-Poissonian shot noise can be qualitatively attributed to the competition between fast and slow transport channels.

Spin current and shot noise in single-molecule quantum dots with a phonon mode

In this paper, we investigate the spin-current and its shot-noise spectrum in a single-molecule quantum dot coupled with a local phonon mode. We pay special attention to the effect of the phonon on the quantum transport property. The spin-polarization-dependent current is generated by a rotating magnetic field applied in the quantum dot. Our results show the remarkable influence of phonon mode on the zero-frequency shot noise. The electron-phonon interaction leads to sideband peaks that are located exactly on the integer number of the phonon frequency, and moreover, the peak height is sensitive to the electron-phonon coupling.

Spin current and polarization reversal through a single-molecule magnet with ferromagnetic electrodes

We theoretically study the spin-polarized transport through a single-molecule magnet, which is weakly coupled to ferromagnetic leads, by means of the rate-equation approach. We consider both the ferromagnetic and antiferromagnetic exchange-couplings between the molecular magnet and transported electron-spin in the nonlinear tunneling regime. For the ferromagnetic exchange-coupling, spin current exhibits step- and basin-like behaviors in the parallel and antiparallel configurations respectively. An interesting observation is that the polarization reversal of spin-current can be realized and manipulated by the variation of bias voltage in the case of antiferromagnetic exchange-coupling with antiparallel lead-configuration, which may be useful in the development of spintronic devices, while the bias voltage can only affect the magnitude of spin-polarization in the ferromagnetic coupling.

Spin-polarized quantum transport through a T -shape quantum dot-array: Model of spin splitter

We in this paper study theoretically the spin-polarized quantum transport through a T-shape quantum dot-array by means of transfer-matrix method along with the Green^{,}s function technique. Multi-magnetic fields are used to produce the spin-polarized transmission probabilities and therefore the spin currents, which are shown to be tunable in a wide range by adjusting the energy, and the direction-angle of magnetic fields as well. Particularly the opposite- spin- polarization currents separately flowing out to two electrodes can be generated and thus the system acts as a spin splitter.

Quantum transport through a double Aharonov-Bohm interferometer in the presence of Andreev reflection

Quantum transport through a double Aharonov-Bohm interferometer in the presence of Andreev reflection is investigated in terms of the nonequilibrium Green function method with which the reflection current is obtained. Tunable Andreev reflection probabilities depending on the interdot coupling strength and magnetic flux as well are analysized in detail. It is found that the oscillation period of the reflection probability with respect to the magnetic flux for the double interferometer depends linearly on the ratio of two parts magnetic fluxes

Barrier tunneling time of an electron in graphene

n

Aharonov-Bohm scattering from the hydrodynamical viewpoint

, i.e.,

Screw-pitch effect and velocity oscillation of a domain wall in a ferromagnetic nanowire driven by spin-polarized current.

2(n+1)ensuremath{pi}

Does the Berry phase in a quantum optical system originate from the rotating wave approximation

, while that of a single interferometer is