Effects of Pb doping on structural and electronics properties of Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10}$

TL;DR

This study investigates how lead doping affects the structural and electronic properties of Bi2223 superconductor using DFT calculations, revealing that Pb doping suppresses Bi-O pockets and alters the electronic band structure.

Contribution

It provides a detailed theoretical analysis of Pb doping effects on Bi2223, showing the suppression of Bi-O pockets consistent with experimental observations.

Findings

Pb doping shifts Bi/Pb-O bands to higher energies

Pb doping above 26% eliminates Bi-O pockets in Fermi surface

Structural changes correlate with the presence or absence of Bi-O pockets

Abstract

Pb doping effect in the Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10}$ compound (Bi2223) on the structural and electronic properties were investigated, using the Local Density (LDA) and Virtual Crystal (VCA) approximations within the framework of the Density Functional Theory (DFT), taking as reference the procedure implemented by H.Lin {\it et al.} in the Bi2212 compound [{\it Phys. Rev. Lett.} {\bf 96} (2006) 097001]. Results show that, the incorporation of Pb-dopant in Bi2223 lead a rigid displacement of the Bi/Pb-O bands toward higher energies, with a null contribution at the Fermi level, around the high symmetry point $\overline{\text{M}}$ in the irreducible Brillouin zone, for Pb doping concentration equal to or more than 26\%, avoiding the presence of the so-called Bi-O {\it pockets} in the Fermi surface, in good agreement with angle-resolved photoemission spectroscopy (ARPES) and nuclear magnetic resonance (NMR) experiments, although a slight metallic character of the Bi-O bonds is still observed which would disagree with some experimental reports. The calculations show that the changes on the structural properties are associated to the presence or absence of the Bi-O {\it pockets} in the Fermi surface