Correlating off-stoichiometric doping with nanoscale electronic disorder and quasiparticle interference pattern in high-$T_c$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$

TL;DR

This paper develops a microscopic theory linking off-stoichiometric oxygen doping to nanoscale electronic disorder and quasiparticle interference in high-$T_c$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+eta}$, explaining how dopant types influence electronic inhomogeneity.

Contribution

It introduces a model that explains how different interstitial oxygen dopants cause electronic disorder and quasiparticle interference in the superconductor, based on an extended t-$J$ model and Gutzwiller approximation.

Findings

Dopant location correlates with pairing gap variations.

Oxygen dopants are primary causes of gap disorder.

Nanoscale hole concentration variations lead to electronic inhomogeneity.

Abstract

A microscopic theory is presented for the observed electronic disorder in superconducting Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The essential phenomenology is shown to be consistent with the existence of two types of interstitial oxygen dopants: those serving primarily as charge reserviors and those close to the apical plane contributing both carriers and electrostatic potential to the CuO$_2$ plane. The nonlinear screening of the latter produces nanoscale variations in the doped hole concentration, leading to electronic inhomogeneity. Based on an unrestricted Gutzwiller approximation of the extended t-$J$ model, we provide a consistent explanation of the correlation between the observed dopant location and the pairing gap and its spatial evolutions. We show that the oxygen dopants are the primary cause of both the pairing gap disorder and the quasiparticle interference pattern.