Evidence for a quasi-one-dimensional topological-excitation liquid in Bi 2Sr 2CaCu 2O 8+ x from tunneling spectroscopy

Abstract

Tunneling measurements have been carried out on heavily underdoped and slightly overdoped Bi 2Sr 2CaCu 2O 8+ x (Bi2212) single crystals by using a break-junction technique. We find that in-plane tunneling spectra below T c are the combination of incoherent part from the pseudogap (PG) and coherent quasi-particle (QP) peaks. There is a correlation between the magnitude of the PG and the magnitude of the superconducting gap in Bi2212. Analysis of the data suggests that the tunneling PG in Bi2212 is predominantly a charge-density-wave gap on dynamical charge stripes. We find that the QP peaks appear from the condensation of soliton-like excitations. Thus, we present evidence for a quasi-one-dimensional topological-excitation liquid in Bi2212.