A New Physical Picture of Superconductivity

J. D. Fan；Y. M. Malozovsky

Chinese Journal of Physics

38卷2S期（2000 / 04 / 01）

366 - 370

英文

In this article, it is argued that superconductivity originates from the Coulomb correlation effects between electrons rather than the electron-phonon interaction. The authors have already shown that the factor 2e in the magnetic flux quantization in a superconductor or Josephson effect has nothing o do with Cooper's pairing. Instead, it is a natural consequence of the gauge invariance for electro-magnetic waves and the London equation for a superconductor. Moreover, it was found that the BCS Hamiltonian can be easily deduced from the fermion Hamiltonian in the second quantization formalism using the grouping condition for momentum k + k' = 0, which is usually termed the Cooper condition, (also, for spin σ + σ' = 0), and that the interaction v(k', k) in the Hamiltonian is nothing else, but the interaction between an electron and a hole in momentum (k) space, and should be naturally attractive according to the Coulomb law. In contrast, U in the Hubbard model mist be positive because the Hubbard model describes the behavior of particles in real space. With the re-interpretation of the interaction, the results regarding a gap in the electron energy spectrum and the isotope effect from the BCS theory remain valid. With the new physical picture in mind, one can thus unify the theory for both low- and high-temperature superconductivity.