Superconducting fluctuation and pseudogap phenomena in high- Tc cuprates

Abstract

A number of experiments indicate a sudden decrease in the quasi-particle density of states as the temperature decreases through T ∗ , which is usually far above T c , the superconducting transition temperature. Here we propose this rather sudden change is due to the superconducting fluctuation. When a parameter x( φ), which characterizes the superconducting fluctuation, increases beyond, say 0.25, the effect becomes quite visible with decreasing temperature. This point is given roughly T ∗ ⋍ E F ln( T ∗ T c ) where E F is the Fermi energy (∼ 200 − 100 K) in the underdoped region.