Femtosecond Quasiparticle and Phonon Dynamics in Superconducting YBa2Cu3O7 Studied by Wideband Terahertz Spectroscopy

TL;DR

This study uses wideband terahertz spectroscopy to investigate femtosecond-scale quasiparticle and phonon dynamics in superconducting YBa2Cu3O7, revealing rapid lattice excitation and electron-phonon interactions.

Contribution

It provides new insights into ultrafast electron-phonon coupling and lattice responses in high-temperature superconductors using femtosecond spectroscopy.

Findings

A rapid excitation of apex oxygen vibration within 150 fs

Significant electron-phonon scattering observed

Lattice absorbs major pump energy before quasiparticle thermalization

Abstract

We measure the anisotropic mid-infrared response of electrons and phonons in bulk YBa2Cu3O7 after femtosecond photoexcitation. A line shape analysis of specific lattice modes reveals their transient occupation and coupling to the superconducting condensate. The apex oxygen vibration is strongly excited within 150 fs demonstrating that the lattice absorbs a major portion of the pump energy before the quasiparticles are thermalized. Our results attest to substantial electron-phonon scattering and introduce a powerful concept probing electron-lattice interactions in a variety of complex materials.