Physics of Spin Glass Freezing and Paired Cluster Model of High-Tc   Superconductivity
  We present here a new mechanism of high-T_c (critical temperature) superconductivity. This new model is able to explain all the HTSC (high-T_c superconductivity) properties, like high T_c, origin and nature of NSPG (normal state pseudogap), anomalous superconducting state (SS) energy gap (SSEG) properties, absence of NMR spin relaxation rate coherence peak, existence of NSPG below T_c, nature of high-T_c magnetic superconductivity, external magnetic field (H) dependence of the NSPG formation temperature T^*, etc. The coexistence of NSPG and SS BCS enegy gap (EG), below T_c, has been predicted by the model before its experimental observation, showing that the observed SSEG is a superposition of NSPG and SS BCS EG. The model, called the paired cluster (PC) model, is also able to explain the pseudogap critical concentration, vortex core pseudogap and possible stripe phase in high-T_c superconductors. We do not find any experimental observation which is not in favour of the model. Their results follow as a natural consequence of the physical picture contained in the model. Several such results are discussed. 
J. K. Srivastava (Tata Institute of Fundamental Research, Mumbai,   India)