Femtosecond x rays link melting of charge-density wave correlations and light-enhanced coherent transport in YBa2Cu3O6.6

TL;DR

This study demonstrates that femtosecond x-ray techniques can induce ultrafast melting of charge density wave correlations in YBa2Cu3O6.6, revealing a competition between charge order and superconductivity that can be manipulated by light.

Contribution

It provides direct experimental evidence linking light-enhanced coherent transport to the melting of charge density wave correlations in a high-temperature superconductor.

Findings

At least 50% of charge density wave order is melted by optical excitation.

Enhanced interlayer transport correlates with suppression of charge order.

Charge ordering and superconductivity may compete, with the latter accessible via nonlinear phonon excitation.

Abstract

We use femtosecond resonant soft x-ray diffraction to measure the optically stimulated ultrafast changes of charge density wave correlations in underdoped YBa2Cu3O6.6. We find that when coherent interlayer transport is enhanced by optical excitation of the apical oxygen distortions, at least 50% of the in-plane charge density wave order is melted. These results indicate that charge ordering and superconductivity may be competing up to the charge ordering transition temperature, with the latter becoming a hidden phase that is accessible only by nonlinear phonon excitation.