Quantum Statistical Theory of Superconductivity in MgB₂  

作　　者：S. Fujita A. Suzuki Y. Takato S. Fujita;A. Suzuki;Y. Takato(Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, USA;Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo, Japan;Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan)

机构地区：[1]Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, USA [2]Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo, Japan [3]Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan

出　　处：《Journal of Modern Physics》2016年第12期1546-1557,共13页现代物理（英文）

摘　　要：A quantum statistical theory of the superconductivity in MgB₂ is developed regarding it as a member of the graphite intercalation compound. The superconducting temperature T_c for MgB₂, C₈K ≡ KC₈, CaC₆, are 39 K, 0.6 K, 11.5 K, respectively. The differences arise from the lattice structures. In the plane perpendicular to the c-axis, B’s form a honeycomb lattice with the nearest neighbour distance while Mg’s form a base-hexagonal lattice with the nearest neighbour distance above and below the B-plane distanced by . The more compact B-plane becomes superconducting due to the electron-phonon attraction. Starting with the generalized Bardeen- Cooper-Schrieffer (BCS) Hamiltonian and solving the generalized Cooper equation, we obtain a linear dispersion relation for moving Cooper pairs. The superconducting temperature T_c identified as the Bose-Einstein condensation temperature of the Cooper pairs in two dimensions is given by , where is the Cooper pair density, the Boltzmann constant. The lattices of KC₈ and CaC₆ are clearly specified.A quantum statistical theory of the superconductivity in MgB₂ is developed regarding it as a member of the graphite intercalation compound. The superconducting temperature T_c for MgB₂, C₈K ≡ KC₈, CaC₆, are 39 K, 0.6 K, 11.5 K, respectively. The differences arise from the lattice structures. In the plane perpendicular to the c-axis, B’s form a honeycomb lattice with the nearest neighbour distance while Mg’s form a base-hexagonal lattice with the nearest neighbour distance above and below the B-plane distanced by . The more compact B-plane becomes superconducting due to the electron-phonon attraction. Starting with the generalized Bardeen- Cooper-Schrieffer (BCS) Hamiltonian and solving the generalized Cooper equation, we obtain a linear dispersion relation for moving Cooper pairs. The superconducting temperature T_c identified as the Bose-Einstein condensation temperature of the Cooper pairs in two dimensions is given by , where is the Cooper pair density, the Boltzmann constant. The lattices of KC₈ and CaC₆ are clearly specified.

关 键 词：Crystal Structure BCS Hamiltonian Electron-Phonon Interaction Cooper Pairs Bose-Einstein Condensation SUPERCONDUCTIVITY 

分 类 号：O17[理学—数学]