New metal-insulator transitions induced by strong defect-phonon-carrier and electron-phonon interactions in doped high-T-c oxides and other non-metallic solids

摘要

Unlike the correlation-induced Mott transition and disorder-induced Anderson one which appear to hold for a weak localization limit, we have studied the new types of the metal-insulator transitions (MITs) induced by strong defect-phonon-carrier and electron -phonon interactions in doped compounds. We formulate a strong localization limit of the MIT problem by applying the continuum theories of extrinsic (or defect-phonon-assist,ed) and intrinsic (or phonon-assisted) self-trapping of carriers to the doped systems. We find that the criterion for the doping induced MIT gives the critical doping concentration x(c) = 0.06 for La2-xSrxCuO4 in accordance with observations. Key differences between the MITs in amorphous and crystalline doped systems are discussed. [References: 11]