STABILITY OF LARGE OPTICAL SINGLET BIPOLARONS, MANY-PARTICLE EFFECTS AND HIGH TEMPERATURE SUPERCONDUCTIVITY

Abstract

The stability criteria for large optical bipolarons are obtained variationally for the entire range of the coupling parameters in both two and three dimensions. The size and the effective mass of these bipolarons are calculated and their variations with the material parameters are discussed. Two compounds are suggested which in the form of thin films should be tested for large bipolaronic effects. The theory is finally applied to La ₂ CuO ₄ and some of its normal state and superconductive properties are explained using the large bipolaronic mechanism.