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Green's Function Technique (green + function_technique)

Distribution by Scientific Domains
Physics and Astronomy80%

Selected Abstracts

Spin-polarized resonant tunneling through two coupled quantum dots

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2006
P. Trocha
Abstract Resonant electronic transport through two coupled non-interacting single-level quantum dots attached to ferromagnetic leads with collinear magnetizations is analyzed theoretically. Coupling of the dots to external leads as well as the inter-dot coupling are assumed to be spin dependent. Basic transport characteristics, including current-voltage curves, linear and nonlinear conductance, and tunnel magnetoresistance associated with magnetization rotation are calculated using the Green function technique. The relevant Green functions have been calculated by the equation of motion method. Variation of the transport characteristics with such system parameters like energy level position, spin polarization of the leads, and coupling between the dots has been calculated numerically. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Tuning of electron transport through molecular bridge systems: A study of shot noise

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2008
Santanu K. Maiti
Abstract We study electron transport characteristics through a single phenalenyl molecule attached with two nonsuperconducting electrodes by the use of Green's function technique. Parametric calculations are given based on the tight-binding model to characterize the electron transport through such molecular bridge system. It is observed that the electron transport properties are significantly influenced by (a) the interference effect and (b) the molecule-to-electrodes coupling strength. In this context we also describe the noise power of the current fluctuations that provides an important information about the electron correlation, which is obtained by calculating the Fano factor (F). The knowledge of this current fluctuations gives a key idea for fabrication of efficient molecular devices. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source]

Electric field control of magnetic properties in multiferroic thin films

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2010
St. Kovachev
Abstract The influence of the electric field E on the magnetic properties in multiferroic thin films is studied by a combination of modified Heisenberg and transverse Ising models (TIMs) using a Green's function technique. It is shown that the magnetization M, the Néel temperature TN and the spin-wave energies Em increase, whereas their damping decreases with increase in electric field E. This is an evidence for the strong intrinsic magnetoelectric (ME) coupling. [source]

Quantum pumps formed of double walled carbon nanotubes

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009
V. Zólyomi
Abstract Using the Brouwer formula, we employ Green's function technique to study charge pumping in shuttle geometry double walled carbon nanotubes. We find strong chirality dependence, and that there is virtually no pumping if the chiral angle of the two walls is the same. We discuss which are the optimal chiralities that can be used for such quantum pumps. Furthermore, we argue that charge pumping with double walled tubes can be used to probe the strength of the inter-layer coupling between the inner and outer nanotube. [source]

Influence of substrates on the statical and dynamical properties of ferroelectric thin films

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2007
J. M. Wesselinowa
Abstract Based on the transverse Ising model using a Green's function technique it is shown that the influence of the substrate induces strong changing of various statical and dynamical properties due to different exchange interactions between the ferroelectric thin film and the substrate. Properties such as the phase transition temperature, the polarization, the soft-mode energy, the damping and the dielectric function were found to be highly dependent upon the magnitude and the kind (tensile or compressive) of the stress due to the substrate. There is some competition between the surface and substrate effects. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]