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

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.