Analysis of the pseudogap-related structure in tunneling spectra of superconductingBi2Sr2CaCu2O8+δrevealed by the break-junction technique

Abstract

The tunnel conductance $G(V)$ for break junctions made of single-crystal as-grown ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ samples with ${T}_{c}\ensuremath{\approx}86--89\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ were measured and clear-cut dip-hump structures (DHSs) were found in the range $80--120\phantom{\rule{0.3em}{0ex}}\mathrm{mV}$ of the bias voltage $V$. A theory of tunneling in symmetrical junctions between inhomogeneous charge-density-wave (CDW) superconductors, considered in the framework of the $s$-pairing model, has been developed. CDWs have been shown to be responsible for the appearance of the DHS in the tunnel current-voltage characteristics and properly describe the experimental results.