Electronic Structure and High Tc Superconductivity in the Cuprates
The origin of superconductivity in the cuprates is attributed to free carriers in the CuO2 planes. These planes are weakly coupled in the c direction so that their electronic properties are nearly 2D. Electrons in a 2D periodic potential show a logarithmic singularity in the density of states called the van Hove singularity (v.H.s.). We assume that the Fermi level lies in the v.H.s. for optimum doping (highest T c). We develop this van Hove scenario and compare its theoretical predictions to experiments.
We show that it explains, high T c’s, variation of T c with doping, anomalous isotope effect, marginal Fermi liquid properties, and very small coherence length. We also take into account the Coulomb repulsion between electrons and show that it does not kill superconductivity if the v.H. peak is above a wide band. Finally we show that in this model we have two stable phases for half filling and optimum doping and perhaps phase separation for intermediate doping.
KeywordsAnisotropy Mercury Coherence
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