Coherent state and superconductivity in the free carrier-bipolaron interacting system |
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| Institution: | 1. Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia;2. Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, ON, Canada N6G 5B8;1. Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering (DEEE), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India;2. Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Technology (CSIR-IICT) Campus, Hyderabad, India;1. Fluminense Federal University (UFF), Electrical Engineering Department, Niterói, Rio de Janeiro, Brazil;2. Electrical Energy Research Center (CEPEL), Rio de Janeiro, Rio de Janeiro, Brazil;3. Rio de Janeiro Federal University (UFRJ), Electrical Engineering Department, Rio de Janeiro, Rio de Janeiro, Brazil;1. Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan;2. Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan;3. Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan;4. Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan |
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| Abstract: | In this paper a model to describe the free carrier-bipolaron interacting system is proposed. Effective hopping of the bipolaron is studied in the slave-boson approach, and a characteristic temperature T1 is obtained, below which the system enters a coherent state. The density of states in the normal state and the superconductivity of the system are discussed in a quasiparticle picture. The results show that the mixing between the free carrier and the bipolaron results in an enhancement of the effective mass of the quasiparticle and meanwhile the renormalized coupling interaction, arising from the negative correlation energy in the bipolaron region, enhances the effective superconducting coupling interaction. Under the most favourable conditions, the superconducting transition temperature Tc ∼ ωc, where ωc is the Debye frequency related with local electron-phonon coupling. In general we have T1 > Tc ⪢ Tc0 (Tc0 is the superconducting transition temperature of a usual superconductor). Therefore the system will firstly enter a coherent state before becoming a high-Tc superconductor. |
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