STM/STS study on large pseudogap and nodal superconducting gap in Bi2201(La) and Bi2212

TL;DR

This study uses STM/STS to investigate the pseudogap and superconducting gap in Bi2201(La) and Bi2212, revealing their relation to charge order and superconducting transition temperature.

Contribution

It provides new insights into the origin of the pseudogap and its connection to charge order and superconductivity in cuprates.

Findings

Large pseudogap linked to charge order in antinodal region

Nodal d-wave gap scales with critical temperature T_c

Homogeneous nodal gap unaffected by pseudogap

Abstract

In the present work, scanning tunneling microscopy/spectroscopy (STM/STS) measurements were carried out on underdoped $\rm Bi_2Sr_{2-{\it x}}La_{\it x}CuO_{6+\delta}$ and $\rm Bi_2Sr_2CaCu_2O_{8+\delta}$ to clarify the origin of the pseudogap, in particular, the inhomogeneous large pseudogap. The nodal part of a d-wave pairing gap, which is under no influence of the inhomogeneous large pseudogap, was also examined by relating the homogeneous bottom part of the STS gap to a nodal d-wave gap in momentum space. We report that the inhomogeneous large pseudogap in the antinodal region links to a two-dimensional electronic charge order, and that the gap size of the nodal d-wave part $\rm {\Delta}_{sc}$ scales with the superconducting critical temperature $\rm {\it T}_c$ in the pseudogap regime.