The effect of hydrostatic pressure ($P$) on charge density waves (CDWs) in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{\mathrm{y}}$ has recently been controversial. Using NMR, we find that both the short-range CDW in the normal state and the long-range CDW in high fields are, at most, slightly weakened at $P=1.9$ GPa. This result is in contradiction with x-ray-scattering results finding complete suppression of the CDW at $\approx 1$ GPa and we discuss possible explanations of this discrepancy. Quantitative analysis, however, shows that the NMR data are not inconsistent with a disappearance of the CDW on a larger pressure scale, typically $\approx 10$–20 GPa. We also propose a simple model reconciling transport data with such a hypothesis, provided the pressure-induced change in doping is taken into account. We conclude that it is therefore possible that most of the spectacular increase in $T_c$ upon increasing pressure up to $\approx 15$ GPa arises from a concomitant decrease of CDW strength.

• Received 20 March 2019

DOI:https://doi.org/10.1103/PhysRevB.100.094502