Topic
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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, it was shown that bipolaron formation leads to a d-wave Bose-Einstein condensate in cuprates owing to the bipolaron energy dispersion rather than to a particular pairing interaction.
Abstract: As has been recently established, bipolaron formation leads to a d-wave Bose–Einstein condensate in cuprates owing to the bipolaron (center-of-mass) energy dispersion rather than to a particular pairing interaction. We show that the unusual low-temperature-dependence of the magnetic field penetration depth λ ( T ) in cuprates can be explained within the bipolaron scenario as well. Both linear positive and negative slopes of λ ( T ) occur depending on the random field profile and amount of disorder.
4 citations
TL;DR: In this paper, it was shown that a bipolaron superconductivity with the transition temperature T c ǫ = 6 − − 20 K can take place in DNA, and that transition temperature depends on the parameter values of the model.
4 citations
TL;DR: In this article, a relation is established between the variational principle and the virial theorem optimizing the electronic wave functions, and it is established that a step-by-step increase in the flexibility of the wave function due to the electron correlations does not stabilize a one-center bipolaron.
Abstract: We give an overview of studies a bipolaron stability by variational method. For bipolaron formations, a relation is established between the variational principle and the virial theorem optimizing the electronic wave functions. We present a large number of qualitative and quantitative arguments, which indicate that the Landau-Pekar bipolaron is an axially-symmetrical formation. Much attention is paid to the analysis of the influence of the Coulomb electron-electron correlations on the stability of a large bipolaron. In detail we analyzed the criteria for determining the optimal wave functions. It is established that a step-by-step increase in the flexibility of the electronic wave function due to the electron correlations does not stabilize a one-center bipolaron. We show after into account of electron-electron correlations a singlet bipolaron retains spatial axially-symmetrical. At the same time, the electron-excited triplet states of Landau-Pekar bipolaron have spherical symmetry. The results of Kasirina and Lakhno are based on the onecenter bipolaron model are incorrect. Presented evidence that the correct application of the variational method and correct account of electron-electron correlations only increase the binding energy of the bipolaron but symmetry of Hartree-Fock approximation can not change. We adduce proofs which point to methodological errors of one-center bipolaron model as well as arising from their calculations incorrect physical consequences. As illustrated in this review the axially symmetric Landau-Pekar bipolaron can correctly interpret the experimentally detected spectroscopic data.
4 citations
TL;DR: In this article, the authors reported the temperature and frequency dependence of a.c. conductivity in glassy Se 70 Te 30− x Zn x (x = 0, 2, 4 and 6) alloys in the temperature range 300-500 K and frequency range 1-kHz.
Abstract: The present work reports the temperature and frequency dependence of a.c. conductivity in glassy Se 70 Te 30− x Zn x ( x = 0, 2, 4 and 6) alloys in the temperature range 300–500 K and frequency range 1 kHz. An agreement between experimental and theoretical results suggests that the a.c. conductivity behaviour of the present samples can be successfully explained by correlated barrier hopping (CBH) model. The density of defect states has been determined using this model for all the glassy alloys. The results show that bipolaron hopping dominates over single-polaron hopping in this glassy system. This is explained in terms of lower values of the maximum barrier height for single-polaron hopping.
4 citations
TL;DR: In this article, the Coulomb-Frohlich model was extended towards the strong electron-phonon interaction (EPI), and a charged Bose liquid of small bipolarons was predicted.
Abstract: Extending the BCS theory towards the strong electron-phonon interaction (EPI), a charged Bose liquid of small bipolarons has been predicted by us with a further prediction that the highest superconducting critical temperature is found in the crossover region of the EPI strength from the BCS-like to bipolaronic superconductivity. Later on we have shown that the unscreened (infinite-range) Frohlich EPI combined with the strong Coulomb repulsion create superlight small bipolarons, which are several orders of magnitude lighter than small bipolarons in the Holstein–Hubbard model (HHM) with a zero-range EPI. The analytical and numerical studies of this Coulomb–Frohlich model (CFM) provide the following recipes for room-temperature superconductivity: (a) The parent compound should be an ionic insulator with light ions to form high-frequency optical phonons, (b) the structure should be quasi two-dimensional to ensure poor screening of high-frequency phonons polarized perpendicular to the conducting planes, (c) a triangular lattice is required in combination with strong, on-site Coulomb repulsion to form the small superlight bipolaron, (d) moderate carrier densities are required to keep the system of small bipolarons close to the Bose-Einstein condensation regime. Clearly most of these conditions are already met in the cuprates.
4 citations