Pressure-induced hole doping of the Hg-based cuprate superconductors

TL;DR

This study explores how applying pressure to Hg-based cuprate superconductors increases hole doping and alters electronic structure, affecting their superconducting properties and challenging existing theoretical models.

Contribution

It provides detailed insights into pressure-induced hole doping effects and electronic structure changes in Hg-based cuprates, offering new understanding of their superconducting behavior.

Findings

Pressure induces approximately 0.05 holes per CuO2 layer.

Density of states at the Fermi level doubles under pressure.

The van Hove scenario's applicability is limited by these findings.

Abstract

We investigate the electronic structure and the hole content in the copper-oxygen planes of Hg based high Tc cuprates for one to four CuO2 layers and hydrostatic pressures up to 15 GPa. We find that with the pressure-induced additional number of holes of the order of 0.05e the density of states at the Fermi level changes approximately by a factor of 2. At the same time the saddle point is moved to the Fermi level accompanied by an enhanced k_z dispersion. This finding explains the pressure behavior of Tc and leads to the conclusion that the applicability of the van Hove scenario is restricted. By comparison with experiment, we estimate the coupling constant to be of the order of 1, ruling out the weak coupling limit.