Quantum tunneling cyclic loop in high temperature superconductor probably is the microscopic origin of high temperature superconductivity

Abstract

4-particle (electrons or electrons with hole) or higher order quantum tunneling cyclic loops (QTCLs) in real space may play a key role in high Tc superconductivity. Because of the existence of mixed valences on the CuO 2 plane, the electron/holes in high Tc superconductor are weekly localized and strongly correlated thus able to form QTCL. The QTCLs have k=0 in the center of the mass frame, and a non-zero angular momentum. Each QTCL has total spin S=0. Each QTCL can contain 2 or more Cooper pairs in real space. As a result of the strong correlation between those tunneling loops, high Tc superconductivity will occur if the connectivity of tunneling loops is large enough to form an infinite cluster, under these conditions: T < Tc and H < Hc. This high Tc superconducting transition is strong angular momentum related, is a special kind of percolation transition which is consistent with the experimental results of uniaxial stress experiments and of thermal expansion measurements. This model is consistent with the fact that the coherence length of high temperature superconductor is in the order of 5–20 angstroms. QTCL model is consistent with gauge invariance and the observation of doped carbon 60 superconductors and superfluid 3He.