Abstract
The superconducting phase of the (Hg-1201) and (Hg-1223) cuprates has been investigated by Raman spectroscopy under hydrostatic pressure. Our analysis reveals that the increase of with pressure is slower in the Hg-1223 cuprate compared to Hg-1201 due to a charge carrier concentration imbalance accentuated by pressure in Hg-1223. We find that the energy variation under pressure of the apical oxygen mode from which the charge carriers are transferred to the layer, is the same for both the Hg-1223 and Hg-1223 cuprates and it is controlled by the interlayer compressibility. At last, we show that the binding energy of the Cooper pairs related to the maximum amplitude of the -wave superconducting gap at the antinodes does not follow with pressure. It decreases while increases. In the particular case of Hg-1201, the binding energy collapses from 10 to 2 as the pressure increases up to 10 GPa. These direct spectroscopic observations joined to the fact that the binding energy of the Cooper pairs at the antinodes does not follow either with doping, raises the question of its link with the pseudogap energy scale which follows the same trend with doping.
11 More- Received 25 February 2021
- Revised 11 April 2021
- Accepted 4 May 2021
DOI:https://doi.org/10.1103/PhysRevB.103.195130
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