First-principles electronic structure investigation of HgBa$_{2}$Ca$_{n-1}$Cu$_{n}$O$_{2n+2+x}$ with the SCAN density functional

TL;DR

This study uses first-principles calculations with the SCAN density functional to analyze the electronic, structural, and magnetic properties of Hg-based cuprates up to six CuO2 layers, revealing antiferromagnetic insulating states and potential quantum criticality signatures.

Contribution

It provides detailed first-principles insights into the evolution of electronic and magnetic properties of Hg-based cuprates with varying layer numbers and doping levels, using the SCAN functional.

Findings

Parent compounds are antiferromagnetic insulators with decreasing gap as layers increase.

Structural and electronic properties align with experimental observations.

Enhanced density of states at Fermi level near specific doping suggests quantum criticality.

Abstract

We perform first-principles calculation to study the electronic structure of HgBa$_{2}$Ca$_{n-1}$Cu$_{n}$O$_{2n+2+x}$ copper oxides up to $n = 6$ for the undoped parent compound $(x = 0)$ and up to $n = 3$ for the doped compound $(x > 0)$ by means of the SCAN meta-GGA density functional. Our calculations predict an antiferromagnetic insulator ground state for the parent compounds with an energy gap that decreases with the number of CuO$_{2}$ planes. We report structural, electronic and magnetic order evolution with $x$ which agree with experiments. We find an enhanced density of states at Fermi level at $x \approx 0.25$ for the single-layered compound manifesting in a peak of the Sommerfeld parameter, which recently has been discussed as a possible signature of quantum criticality generic to all cuprates.