Snapshots of the retarded interaction of charge carriers with ultrafast fluctuations in cuprates

TL;DR

This study uses advanced ultrafast spectroscopy to directly observe the rapid 16 femtosecond formation of electron-boson interactions in cuprates, shedding light on the dynamics underlying high-temperature superconductivity.

Contribution

It provides the first direct measurement of the ultrafast timescale of electron-boson interaction build-up in cuprates, confirming theoretical models of magnetic excitation-mediated relaxation.

Findings

Observed 16 fs build-up of electron-boson interaction.

Results agree with t-J and Hubbard model calculations.

Revealed inelastic scattering with antiferromagnetic excitations as relaxation mechanism.

Abstract

One of the pivotal questions in the physics of high-temperature superconductors is whether the low-energy dynamics of the charge carriers is mediated by bosons with a characteristic timescale. This issue has remained elusive since electronic correlations are expected to dramatically speed up the electron-boson scattering processes, confining them to the very femtosecond timescale that is hard to access even with state-of-the-art ultrafast techniques. Here we simultaneously push the time resolution and the frequency range of transient reflectivity measurements up to an unprecedented level that enables us to directly observe the 16 fs build-up of the effective electron-boson interaction in hole-doped copper oxides. This extremely fast timescale is in agreement with numerical calculations based on the t-J model and the repulsive Hubbard model, in which the relaxation of the photo-excited charges is achieved via inelastic scattering with short-range antiferromagnetic excitations.