نتایج جستجو برای: polaron

تعداد نتایج: 1860  

2007
José Rildo de Oliveira Queiroz Geraldo Magela e Silva

Effects of interchain interaction on the polaron-bipolaron transition on conjugated polymer are investigated. We use the Su-Schrieffer-Heeger model combined with the Pariser-Parr-Pople model modified to include interchain interaction, and an external electric field. We study the dynamics within the Time-Dependent Unrestricted HartreeFock approximation. We find that removing an electron from int...

Journal: :Journal of physics. Condensed matter : an Institute of Physics journal 2009
P Ingenhoven R Egger U Zülicke

We present a theory for spin-polarized transport through a generic organic polymer connected to ferromagnetic leads with arbitrary angle θ between their magnetization directions, taking into account the polaron and bipolaron states as effective charge and spin carriers. Within a diffusive description of polaron-bipolaron transport including polaron-bipolaron conversion, we find that the bipolar...

2006
J. T. Devreese

As is generally known, the polaron concept was introduced by Landau in 1933 [1]. Gradually a distinction was made between polarons in the continuum approximation where long-range electron-lattice interaction prevails (“Fröhlich”polarons) and polarons for which the short-range interaction is essential (Holstein, Holstein-Hubbard models). After a period of initial theoretical [1, 2, 3, 4, 5, 6, 7...

2000
P. Quémerais S. Fratini

On examining the stability of a Wigner Crystal (WC) in an ionic dielectric, two competitive effects due to Polaron formation are found to be important: (i) the screening of the Coulomb forces which destabilizes the crystal, compensated by (ii) the increase of the carrier mass (polaron mass). The quantum melting of the Polaron Wigner Crystal (PWC) is examined. By calculating the quantum fluctuat...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2007
Ch Jooss L Wu T Beetz R F Klie M Beleggia M A Schofield S Schramm J Hoffmann Y Zhu

Polarons, the combined motion of electrons in a cloth of their lattice distortions, are a key transport feature in doped manganites. To develop a profound understanding of the colossal resistance effects induced by external fields, the study of polaron correlations and the resulting collective polaron behavior, i.e., polaron ordering and transition from polaronic transport to metallic transport...

2004
Alexander Weiße Holger Fehske Dieter Ihle

Based on the Holstein double-exchange model and a highly efficient single cluster Monte Carlo approach we study the interplay of double-exchange and polaron effects in doped colossal magneto-resistance (CMR) manganites. The CMR transition is shown to be appreciably influenced by lattice polaron formation.

2007
Martin Hohenadler Peter B. Littlewood Holger Fehske

Exciton-polaron formation in one-dimensional lattice models with shortor long-range carrier-phonon interaction is studied by quantum Monte Carlo simulations. Depending on the relative sign of electron and hole-phonon coupling, the exciton-polaron size increases or decreases with increasing interaction strength. Quantum phonon fluctuations determine the excitonpolaron size and yield translation-...

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