Time-Resolved Optical Studies of Quasiparticle Dynamics in High-Temperature Superconductors: Experiments and theory

TL;DR

This paper combines ultrafast optical experiments and theoretical models to study quasiparticle dynamics, superconducting gap symmetry, and pseudogap behavior in high-temperature superconductors across different doping levels and temperatures.

Contribution

It provides a comprehensive analysis of quasiparticle recombination and gap evolution using combined experimental and theoretical approaches in high-Tc superconductors.

Findings

Existence of a temperature-independent gap in underdoped samples

Evolution of the gap into a two-component state near optimal doping

Dominant response from a T-dependent BCS-like gap at optimal doping

Abstract

Ultrafast time-resolved optical spectroscopy in high-temperature superconductors enables the direct real-time measurement of non-equilibrium quasiparticle recombination dynamics. In addition, it also gives detailed information about the symmetry of the superconducting gap and the "pseudogap", their doping dependence and their temperature dependence. Experimental data, together with theoretical models on the photoinduced transmission amplitude and relaxation time as a function of temperature and doping in YBa2Cu3O7-d gives a consistent picture of the evolution of low-energy structure, where a temperature-independent gap is shown to exist in the underdoped state which evolves with doping into a two-component state near optimum doping, where the dominant response is from a T-dependent BCS-like superconducting gap.