Strong correlation, electron–phonon interaction and critical fluctuations: isotope effect, pseudogap formation, and phase diagram of the cuprates Original Research Article

Although structurally the high temperature superconductors are quasi-two-dimensional, there is both theoretical and experimental evidence of a substantial range of temperatures in which ‘stripe’ correlations make the electronic structure locally quasi-one-dimensional. We consider an array of Josephson coupled, spin gapped one dimensional electron gases as a model of the high temperature superconductors. For temperatures above Tc, this system exhibits electron fractionalization, yielding a single particle spectral response which is sharp as a function of momentum, but broad as a function of energy. For temperatures below the spin gap but above Tc, there are enhanced one-dimensional superconducting fluctuations and pseudogap phenomena. Pair tunneling induces a crossover to three-dimensional physics as Tc is approached. Below Tc, solitons are confined in multiplets with quantum numbers which are simply related to the electron, and a coherent piece of the single particle spectral function appears. The weight of this coherent piece vanishes in the neighborhood of Tc in proportion to a positive power of the interchain superfluid density. This behavior is highly reminiscent of recent ARPES measurements on the high temperature superconductors.