Polarons

Appel, J.

doi:10.1016/s0081-1947(08)60741-9

Cited by 322 publications

(59 citation statements)

References 208 publications

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“…21 The inverse value of the relaxation time calculated by ͑22͒ should be added to the inverse time of the SP relaxation in ordinary scattering processes. 25 Relaxation time of DPs and free carriers was calculated by the well-known formulas 25,26 as it was done in Ref. 22.…”

Section: Braking Of Polarons By the Coherent Phonon Radiation Anmentioning

confidence: 99%

Coherence of the lattice polarization in large-polaron motion

Myasnikov¹,

Myasnikova

Kusmartsev

2005

Phys. Rev. B

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Main problems of the large polaron theory are considered. We demonstrate that the problem of searching the ground stationary state of a system of coupled fields with translation-invariant Hamiltonian can have a solution of the form f͑r − vt͒, v → 0, i.e., the solution with the spontaneously broken translational symmetry. Such a state can be a ground state of a large polaron in case of strong electron-phonon coupling when the spontaneous break of the translational symmetry results from the phonon vacuum deformation by the electric field of the charge carrier. The correctness of the classical representation of the polarization field in the theory of a strongly coupled large polaron is proved on the base of the theory of the quantum-coherent states of the phonon field. The use of this representation has enabled us to show that extremely high losses of the electron energy in dielectric parts of cold cathodes occurring when the carrier velocity is lower than the threshold for the single-phonon radiation are due to coherent phonon radiation by polarons like Cherenkov effect. It is this radiation that results in the predicted Thornber and Feynman dependence of the carrier steady-state velocity on the applied electric field strength. The coherent phonon radiation generated by polaron current can be detected in experiments on the neutrons scattering. The primary directions of the neutrons scattering depend on the polarons steady-state velocity and, hence, on the applied field strength. The coherent phonon radiation stemming from supersonic thermal motion of polarons causes a giant increase of the resistance in a corresponding temperature interval.

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Section: Braking Of Polarons By the Coherent Phonon Radiation Anmentioning

confidence: 99%

Coherence of the lattice polarization in large-polaron motion

Myasnikov¹,

Myasnikova

Kusmartsev

2005

Phys. Rev. B

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“…Later Whitfield and Puff 2 suggested an improved version of the polaron energy-momentum relation in the weakcoupling regime. For these and other early papers see also the review article by Appel 3 where qualitative considerations on the behavior of the dispersion curve were given. The results obtained demonstrate that the bulk polaron energy-momentum relation is quadratic for small Q but then bends over and becomes horizontal when the energy approaches the continuum edge E c which is reached at some finite value Q c of the polaron momentum.…”

Section: Introductionmentioning

confidence: 99%

Upper and lower bounds for the large polaron dispersion in 1, 2, or 3 dimensions

Gerlach

Smondyrev

2008

Phys. Rev. B

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Numerical results for the polaron dispersion are presented for an arbitrary number of space dimensions. Upper and lower bounds are calculated for the dispersion curves. They are rather close to each other in the cases of small electron-phonon couplings usual for real polar materials. To describe the dispersion in other materials, we suggest a simple fitting formula which can be applied at intermediate values of the Fröhlich electron-phonon coupling constant. Its validity is approved by the comparison with direct calculations and previously obtained results. This makes our results not only reliable and highly accurate but also easy reproducible.

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“…The case involving electron-phonon interactions has been discussed by several authors including Appel 45 and Davydov. 46 The purely electronic effects were treated in earlier works 2,23 in which we calculated the renormalization effect due to the electronic polarizability in the bulk of the organic semiconductor.…”

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Quantum coherence and carriers mobility in organic semiconductors

2007

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We present a model of charge transport in organic molecular semiconductors based on the effects of lattice fluctuations on the quantum coherence of the electronic state of the charge carrier. Thermal intermolecular phonons and librations tend to localize pure coherent states and to assist the motion of less coherent ones. Decoherence is thus the primary mechanism by which conduction occurs. It is driven by the coupling of the carrier to the molecular lattice through polarization and transfer integral fluctuations as described by the hamiltonian of Gosar and Choi.1 Localization effects in the quantum coherent regime are modeled via the Anderson hamiltonian with correlated diagonal and non-diagonal disorder 2 leading to the determination of the carrier localization length. This length defines the coherent extension of the ground state and determines, in turn, the diffusion range in the incoherent regime and thus the mobility. The transfer integral disorder of Troisi and Orlandi 3 can also be incorporated. This model, based on the idea of decoherence, allowed us to predict the value and temperature dependence of the carrier mobility in prototypical organic semiconductors that are in qualitative accord with experiments.

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Polarons

Cited by 322 publications

References 208 publications

Coherence of the lattice polarization in large-polaron motion

Coherence of the lattice polarization in large-polaron motion

Upper and lower bounds for the large polaron dispersion in 1, 2, or 3 dimensions

Quantum coherence and carriers mobility in organic semiconductors

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