Charge-spin separation, spin-excitation spectrum, and the normal-state properties of the copper oxide superconductors

Abstract

We show that the unusual normal-state properties of the copper oxide superconductors can be derived from the one-band t-J model with the use of a rigorously imposed constraint of single-electron occupancy and the Wigner-Jordan representation of the spin-excitation spectrum. These include the linear resistivity in the ab plane, the 1/T resistivity along the c direction, the anomalous spin-relaxation rate in the Cu site, the excessive absorption in the infrared conductivity over that expected from the Drude theory, the flat electronic Raman background, the broadening of the photoemission spectra, and the linear-bias dependence of the normal-metal–normal-metal tunneling conductance (along the ab plane). The zero-bias tunneling conductance along the ab plane is predicted to have a linear temperature dependence. A particularly interesting prediction is that the ratio of the linear temperature term of the zero-bias conductance to the linear-bias term of the zero-temperature conductance is 2T/‖eV‖, independent of all other parameters. The static spin susceptibility at low temperature is predicted to have the form A+B ln(ωc/T), where ωc∼J is a cutoff energy. The doping (x) dependences of various physical quantities are also predicted for the range of x large enough to allow the holons to form a band and the spins to have a disordered (liquid) ground state, but not too large to destroy the antiferromagnetic spin correlation. The imaginary part of the spin susceptibility has a wave-vector-independent component with an x dependence of x(1-x)2. The nuclear relaxation at the Cu site, 1/(TT1), has a 1/T component with an x dependence of x(1-x)2. The zero-bias tunneling conductance along the ab plane at zero temperature increases with x2. The 1/T resistivity along the c direction at low temperature is inversely proportional to x, and the linear resistivity of the ab plane has a weak x dependence in the doping range mentioned above.

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