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Bipolaron

About: Bipolaron is a research topic. Over the lifetime, 1335 publications have been published within this topic receiving 29154 citations. The topic is also known as: bipolarons.


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Proceedings ArticleDOI
25 Jun 2015
TL;DR: In the weak coupling limit, the 2D Hubbard model extended by on-site and inter-site electron-phonon (EP) interaction has been investigated within Lanczos method of exact diagonalization.
Abstract: In the weak coupling limit, the 2D Hubbard model extended by on-site (local) and inter-site (long range) electron-phonon (EP) interaction has been investigated within Lanczos method of exact diagonalization (ED) On-site (S0) bipolaron formation has been favored by on-site EP interaction induced effective attraction between electrons But, inter-site phonon mediated interaction between electrons helps to form both S0 and neighboring site (S1) bipolaron It is further observed that both types of bipolaron formation are suppressed by on-site Hubbard repulsion

1 citations

Book ChapterDOI
23 Aug 2017
TL;DR: In this article, it is shown that injection of electrons/holes in the conduction band leads to soliton level appearance inside the restricted area and this is accompanied by a marked shift of the valence band top and conduction bands bottom, when electron injected − downward energy, in the case of hole injection.
Abstract: Linear conjugated systems are the systems of connected p-orbitals with delocalized electrons in molecular compounds with the alternation of simple and multiple bonds. In general, the linear conjugated systems, which will be discussed here, can be represented by the formula [R1 – (CH)m – R2], where R1 and R2 are terminal group connected to the polymethine chain. These systems can be either electric neutral and charged positively or negatively, depending on what they injected – electron or hole. Methine carbon atom of (CH) in the chain is in sp2-hybridized state. To explain the properties of some organic compounds such as quasi-metallic conductivity, a significant change in the spectral properties of ionic dyes that absorb and emit light in the near infrared region of the spectrum [1, 2, 3, 4] managed, including through the use of the concept of solitons. It is established that injection of electrons/holes in the conduction band leads to soliton level appearance inside the restricted area and this is accompanied by marked shift of the valence band top and the conduction band bottom, when electron injected – downward energy, in the case of hole injection – in the direction of energy increasing [1, 2, 3, 4]. In this work we use the charge transfer model based on the concept of solitons, according to Davidov A. [4] which complements and develops other models [1, 2, 3, 4]. 1. Mishra А. Cyanine during 1990s: А review. Chem. Rev., 2000, 100, p.1973–2011. 2. F.Meyers, S.R.Marder, J.W.Perry, Introducing to Nonlinear Optical Properties Organic Materials. In Chemistry Advanced Materials. An Overreviw. Chapt. 6. Ed. L. V. Interrante, J.Hampden-Smith. 1998. Wiley-VCH. Inc. New York-Chicherster-Weinheim-Brisbane-Singapore-Toronto P.207–268. 3. Bredas J.L., Street G.B. Polaron, bipolaron and solitons in conductiong polymers. Acc.Chem.Res. 1985, 18, 309–315. 4. 4. Davydov A. S. (1973). “The theory of contraction of proteins under their excitation”. Journal of Theoretical Biology 38 (3): 559–569. doi:10.1016/0022-5193(73)90256-7. PMID 4266326.

1 citations

Book ChapterDOI
L.J. de Jongh1
01 Jan 1991
TL;DR: In this paper, a model of sufficient generality to explain the overall properties of various types of metal oxide superconductors known at present is discussed, and the mobility of these polarons and bipolarons is governed by the principles of mixed-valence (polaronic) charge transfer.
Abstract: We discuss a model of sufficient generality to explain qualitatively the overall properties of the various types of metal oxide superconductors known at present. These materials are polar semiconductors, with intrinsic gaps of a few eV. Doping or self-doping leads to p- or n-type extrinsic conductivity in, respectively, an acceptor or a donor impurity band inside the gap. Compensation effects have been observed. The metal-nonmetal transition at low doping levels is of the Mott-Anderson type. The carriers are charged molecular defects that can be seen as mixed-valence small-polarons. They may carry a single or double charge, depending on whether the metal atom involved has a tendency to disproportionate or not. If it has, then the doubly charged polaron is an onsite bipolaron, which is a local singlet pair of charges. If not, then local pairs may only be formed under certain conditions by coupling two, singly charged polarons into an intersite bipolaron. The mobility of these polarons and bipolarons is governed by the principles of mixed-valence (polaronic) charge transfer. The moving bipolarons can be viewed as weakly interacting, charged Bose quasiparticles hopping on a lattice, and will Bose-condense into a superfluid state at sufficiently low temperatures.

1 citations

Journal ArticleDOI
TL;DR: By exact diagonalization of a small cluster, this article showed that an interplay of electron-phonon and onsite electron-electron interactions results in "intersite" or "onsite" two-electrons (bipolaronic) solutions of the Holstein-Hubbard model, depending on the strengths of the interactions.
Abstract: By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and onsite electron–electron interactions results in “intersite” or “onsite” two-electron (bipolaronic) solutions of the Holstein–Hubbard model, depending on the strengths of the interactions. On this basis, we argue that the decrease in the superconducting transition temperature of Bi-2212 compounds, following the enhancement of the electron–phonon interaction recently reported by Devereaux et al. [10] might be a consequence of the above mechanism, which leads to a transition from itinerant (intersite) to bound immobile (onsite) bipolarons, thus effectively reducing the number of superconducting carriers.

1 citations

Journal ArticleDOI
TL;DR: In this paper, the in-plane resistivity ρ ab (T) and the out-of-plane ρ c(T) have been extensively measured for pure single crystal Bi 2Sr 2CaCu 2O 8+ δ (Bi2212) annealed at different oxygen pressures.
Abstract: The in plane resistivity ρ ab (T) and the out of plane ρ c(T) have been extensively measured for pure single crystal Bi 2Sr 2CaCu 2O 8+ δ (Bi2212) annealed at different oxygen pressures.The ρ c(T) and anisotropy ( ρ c(T)/ρ ab (T)) decrease rapidly with increasing carrier concentration.It is found that the out of plane resistivity decreases linearly with decreasing temperature down to about 120K for the overdoped sample,its resistivity anisotropy is of weak temperature dependence.The data of ρ c(T) and ρ c(T)/ρ ab (T) are well fitted by the bipolaron theory proposed by Alexandrov and Mott.

1 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202229
202127
202023
201920
201833