Modification of structural disorder by hydrostatic-pressure in superconducting YBa$_{2}$Cu$_{3}$O$_{6.73}$ cuprate

TL;DR

This study investigates how hydrostatic pressure influences the structural disorder and oxygen ordering in YBa2Cu3O6.73, revealing mechanisms that enhance its superconducting transition temperature and potential for nematic order transition.

Contribution

It demonstrates that hydrostatic pressure reinforces oxygen order and modifies disorder in YBCO, providing insights into pressure-induced $T_c$ enhancement and nematic order transition mechanisms.

Findings

Oxygen order is reinforced under hydrostatic pressure.

No charge density wave signature observed under pressure.

Pressure modifies disorder, potentially facilitating nematic order transition.

Abstract

Compelling efforts to improve the critical temperature ($T_{c}$) of superconductors have been made through high-pressure application. Understanding the underlying mechanism behind such improvements is critically important, however, much remains unclear. Here we studied ortho-III YBa$_{2}$Cu$_{3}$O$_{6.73}$ (YBCO) using x-ray scattering under hydrostatic-pressure (HP) up to ~6.0 GPa. We found the reinforced oxygen order (OO) of YBCO under HP, revealing an oxygen rearrangement in the Cu-O layer, which evidently shows the charge transfer phenomenon between the CuO$_{2}$ plane and Cu-O layer. Concurrently, we also observed no disorder-pinned charge density wave (CDW) signature in CuO$_{2}$ plane under HP. This indicates that the oxygen rearrangement modifies the quenched disorder state in the CuO$_{2}$ plane. Using these results, we appropriately explain why pressure-condition can achieve higher $T_{c}$ compared with the optimal $T_{c}$ under ambient pressure in YBa$_{2}$Cu$_{3}$O$_{6+x}$. As an implication of these results, finally, we have discussed that the change in disorder could make it easier for YBa$_{2}$Cu$_{3}$O$_{6+x}$ to undergo a transition to the nematic order under an external magnetic field.