Abstract
Compelling efforts to improve the critical temperature 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 (YBCO) using x-ray scattering under hydrostatic pressure (HP) up to . We found the reinforced oxygen order of YBCO under HP, revealing an oxygen rearrangement in the Cu-O layer, which evidently shows the charge-transfer phenomenon between the plane and Cu-O layer. Concurrently, we also observed no disorder-pinned charge-density-wave signature in plane under HP. This indicates that the oxygen rearrangement modifies the quenched disorder state in the plane. Using these results, we appropriately explain why pressure condition can achieve higher compared with the optimal under ambient pressure in . As an implication of these results, finally we have discussed that the change in disorder could make it easier for to undergo a transition to the nematic order under an external magnetic field.
- Received 18 September 2017
- Revised 16 April 2018
DOI:https://doi.org/10.1103/PhysRevB.97.174508
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