The physical mechanism of superconductivity is proposed on the basis of carrier-induced dynamic strain effect. By this new model, superconducting state consists of the dynamic bound state of superconducting electrons, which is formed by the high-ener
gy nonbonding electrons through dynamic interaction with their surrounding lattice to trap themselves into the three - dimensional potential wells lying in energy at above the Fermi level of the material. The binding energy of superconducting electrons dominates the superconducting transition temperature in the corresponding material. Under an electric field, superconducting electrons move coherently with lattice distortion wave and periodically exchange their excitation energy with chain lattice, that is, the superconducting electrons transfer periodically between their dynamic bound state and conducting state. Thus, the intrinsic feature of superconductivity is to generate an oscillating current under a dc voltage. The coherence lengths in cuprates must have the value equal to an even number times the lattice constant. A superconducting material must simultaneously satisfy three criteria required by superconductivity. Almost all of the puzzling behavior of the cuprates can be uniquely understood under this new model. We demonstrate that the factor 2 in Josephson current equation, in fact, is resulting from 2V, the voltage drops across the two superconductor sections on both sides of a junction, not from the Cooper pair, and the magnetic flux is quantized in units of h/e, postulated by London, not in units of h/2e. The central features of superconductivity, such as Josephson effect, the tunneling mechanism in multijunction systems, and the origin of the superconducting tunneling phenomena, are all physically reconsidered under this superconductivity model.
