Effects of Ba doping on the structural and electronic properties of La$_{2-x}$Ba$_x$CuO$_4$

TL;DR

This study uses first-principles calculations to explore how Ba doping affects the structural and electronic properties of La$_{2-x}$Ba$_x$CuO$_4$, revealing changes in band structure, Fermi surface topology, and implications for superconductivity.

Contribution

It provides a detailed first-principles analysis of Ba doping effects on La$_{2-x}$Ba$_x$CuO$_4$, highlighting changes in electronic structure and Fermi surface topology.

Findings

Ba doping causes bands to shift to higher energies.

Fermi surface topology changes with doping, matching experimental ARPES data.

Increased Cu d$_{z^{2}}$ states at the Fermi level suppress superconductivity.

Abstract

The structural and electronic properties of La$_{2-x}$Ba$_x$CuO$_4$ were investigated as a function of Ba-concentration $0 \leq x \leq 1.2$, within the virtual crystal approximation (VCA) by means of first-principles total-energy calculations. We found Ba doping induces a quasi-rigid displacement of Cu d$_{x^{2}-y^{2}}$ and d$_{z^{2}}$ bands toward higher energies. This effect generates important changes in the Fermi surface topology, which manage to imitate the ARPES momentum distribution map (MDM) measurements and tight-binding calculations recently reported for doped La-based cuprates. The calculations exhibit the significant increase in the contribution of Cu d$_{z^{2}}$ states at the Fermi level for greater Ba doping content to 0.3, which has effects on orbital hybridisation with Cu d$_{x^{2}-y^{2}}$ states and therefore in the suppression of the superconducting state. For this Ba doping range, no magnetism was found.