Electromagnetic response of high-Tc superconductors: Slave-boson and doped-carrier theories

Abstract

We evaluate the doping dependence of the quasiparticle current and low-temperature superfluid density in two slave-particle theories of the tt′t″J model—the slave-boson theory and doped-carrier theory. In the slave-boson theory, the nodal quasiparticle current renormalization factor α proportionally vanishes to the zero temperature superfluid density ρS(0); however, we find that away from the ρS(0)→0 limit, α displays a much weaker doping dependence than ρS(0). A similar conclusion applies to the doped-carrier theory, which differentiates the nodal and antinodal regions of momentum space. Due to its momentum space anisotropy, the doped-carrier theory enhances the value of α in the hole doped regime, bringing it to quantitative agreement with experiments, and reproduces the asymmetry between hole and electron doped cuprate superconductors. Finally, we use the doped-carrier theory to predict a specific experimental signature of local staggered spin correlations in doped Mott insulator superconductors, which, we propose, should be observed in scanning tunneling microscopy measurements of underdoped high-Tc compounds. This experimental signature distinguishes the doped-carrier theory from other candidate mean-field theories of high-Tc superconductors, such as the slave-boson theory and the conventional BCS theory.

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