Single-Particle Pseudogap in Two-Dimensional Electron Systems

We investigate pseudogap phenomena in the 2D electron system. Based on the mode-mode coupling theory of antiferromagnetic (AFM) and $d_{x^2-y^2}$-wave superconducting ($d$SC) fluctuations, single-particle dynamics is analyzed. For the parameter values of underdoped cuprates, pseudogap structure grows in the single-particle spectral weight $A(k,\omega)$ around the wave vector $(\pi,0)$ and $(0,\pi)$ below the pseudo-spin-gap temperature $\TPG$ signaled by the reduction of dynamical spin correlations in qualitative agreement with the experimental data. The calculated results for the overdoped cuprates also reproduce the absence of the pseudogap in the experiments. We also discuss limitations of our weak-coupling approach.