Charge order and suppression of superconductivity in HgBa2CuO4 at high pressures

TL;DR

This study investigates how high pressure affects superconductivity in HgBa2CuO4, revealing that charge ordering emerges at 10GPa and suppresses superconductivity above 13GPa, marking a first observation of charge order competing with superconductivity in this cuprate.

Contribution

It provides the first direct evidence of charge order competing with superconductivity in HgBa2CuO4 under high pressure, using combined resistivity and X-ray diffraction measurements.

Findings

Superconductivity is suppressed above 13GPa due to charge order.

Charge ordering appears at 10GPa with a specific wavevector.

Pressure induces a charge transfer of about 0.02 at 10GPa.

Abstract

New insight into the superconducting properties of HgBa2CuO4 (Hg-1201) cuprates is provided by combined measurements of the electrical resistivity and single crystal X-ray diffraction under pressure. The changes induced by increasing pressure up to 20GPa in optimally doped single crystals were investigated. The resistivity measurements as a function of temperature show a metallic behavior up to ~10GPa that gradually passes to an insulating state, typical of charge ordering, that totally suppresses superconductivity above 13GPa. The changes in resistivity are accompanied by the apparition of sharp Bragg peaks in the X-ray diffraction patterns indicating that the charge ordering is accompanied by a 3D oxygen ordering appearing at 10GPa of wavevector [0.25, 0, L]. As pressure induces a charge transfer of about 0.02 at 10GPa, our results are the first observation of charge order competing with superconductivity that develops in the over-doped region of the phase diagram of a cuprate.