Femtosecond quasiparticle relaxation dynamics and probe polarization anisotropy in YBa2Cu4O8

TL;DR

This study uses femtosecond pump-probe experiments to investigate quasiparticle relaxation dynamics and probe polarization anisotropy in YBa2Cu4O8, revealing distinct relaxation components linked to superconductivity and the pseudogap, with notable polarization effects.

Contribution

It provides new insights into the polarization anisotropy and relaxation dynamics in YBa2Cu4O8, extending understanding from similar compounds like YBa2Cu3O7-.

Findings

Two-component relaxation related to superconducting transition and pseudogap.

Pseudogap relaxation time is temperature-independent.

Strong polarization anisotropy observed below Tc.

Abstract

Femtosecond pump probe experiments are reported on quasiparticle relaxation and recombination in YBa2Cu4O8 as a function of temperature and polarization. The data show a 2-component relaxation similar to YBa2Cu3O7-\delta, one component being assocated with the superconducting transition, and the other with the pseudogap below T* The relaxation time tau_p associated with the pseudogap is found to be T-independent, while the relaxation time tau_g of the component obseved only below Tc exhibits a clear divergence near Tc. A strong polarisation anisotropy of the picosecond transient is observed below Tc which is attributed to the anisotropy of the probe transition matrix elements.