Direct Role of Structural Dynamics in Electron-Lattice Coupling of Superconducting Cuprates

TL;DR

This study provides direct evidence that specific structural dynamics, particularly buckling of copper-oxygen planes, play a crucial role in the anisotropic electron-lattice coupling in high-temperature superconducting cuprates, with implications for understanding electron pairing mechanisms.

Contribution

It demonstrates the direct involvement of selective atomic motions in electron-lattice coupling using time-resolved electron diffraction, revealing their dynamical role in high-temperature superconductivity.

Findings

Selective atomic motions reach 0.5% deformation amplitude.

Electron-lattice coupling occurs on a 1 to 3.5 ps timescale.

Structural dynamics are anisotropic and polarization-dependent.

Abstract

The mechanism of electron pairing in high-temperature superconductors is still the subject of intense debate. Here, we provide direct evidence of the role of structural dynamics, with selective atomic motions (buckling of copper-oxygen planes), in the anisotropic electronlattice coupling. The transient structures were determined using time-resolved electron diffraction, following carrier excitation with polarized femtosecond heating pulses, and examined for different dopings and temperatures. The deformation amplitude reaches 0.5 % of the c-axis value of 30 A when the light polarization is in the direction of the copper-oxygen bond, but its decay slows down at 45 degrees. These findings suggest a selective dynamical lattice involvement with the anisotropic electron-phonon coupling being on a time scale (1 to 3.5 ps depending on direction) of the same order of magnitude as that of the spin exchange of electron pairing in the high-temperature superconducting phase.