Hague, J. P.; Kornilovitch, P. E.; Samson, J. H. and Alexandrov, A. S.
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|DOI (Digital Object Identifier) Link:||http://doi.org/10.1088/0953-8984/19/25/255214|
|Google Scholar:||Look up in Google Scholar|
Recent angle-resolved photoemission spectroscopy (ARPES) has identified that a finite-range FrÃ¶hlich electron–phonon interaction (EPI) with c-axis polarized optical phonons is important in cuprate superconductors, in agreement with an earlier proposal by Alexandrov and Kornilovitch. The estimated unscreened EPI is so strong that it could easily transform doped holes into mobile lattice bipolarons in narrow-band Mott insulators such as cuprates. Applying a continuous-time quantum Monte Carlo algorithm (CTQMC), we compute the total energy, effective mass, pair radius, number of phonons and isotope exponent of lattice bipolarons in the region of parameters where any approximation might fail, taking into account the Coulomb repulsion and the finite-range EPI. The effects of modifying the interaction range and different lattice geometries are discussed with regards to analytical strong-coupling/non-adiabatic results. We demonstrate that bipolarons can be simultaneously small and light, provided suitable conditions on the electron–phonon and electron–electron interactions are satisfied. Such light small bipolarons are a necessary precursor to high-temperature Bose–Einstein condensation in solids. The light bipolaron mass is shown to be universal in systems made of triangular plaquettes, due to a novel crab-like motion. Another surprising result is that the triplet–singlet exchange energy is of the first order in the hopping integral and that triplet bipolarons are much heavier than singlets in certain lattice structures. Finally, we identify a range of lattices where superlight small bipolarons may be formed, and give estimates for their masses in the anti-adiabatic approximation.
|Item Type:||Journal Article|
|Copyright Holders:||2007 IOP Publishing Ltd|
|Project Funding Details:||
|Extra Information:||27 pp.|
|Academic Unit/Department:||Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Biomedical Research Network (BRN)
|Depositing User:||James Hague|
|Date Deposited:||13 May 2009 14:47|
|Last Modified:||23 Feb 2016 17:30|
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