Van Hove singularity scenario and hole density in CaCuO2: Pressure effects.

Abstract

A first-principles self-consistent full-potential linear muffin-tin orbital theory has been employed to investigate the effect of hydrostatic pressure on the location of the van Hove singularity (vHs) and the concentration of holes in the parent superconductor ${\mathrm{CaCuO}}_{2}$. One finds the pinning of the vHs at the Fermi level for a critical relative volume (V/${\mathit{V}}_{0}$)=0.68, ${\mathit{V}}_{0}$ being the volume at normal pressure. This critical volume corresponds to a pressure of about 40 GPa, which should show up in a large value of ${\mathit{T}}_{\mathit{c}}$ in the experiment. The nested area in the Brillouin zone is maximum for the critical volume. The hole concentration increases with the pressure.