26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Ultrafast studies of dynamics in cuprate superconductors

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Poster AIP | Condensed Matter & Materials (CMM)

Description

High temperature superconductors (HTSCs) have exhibit a wealth of fascinating macroscopic phases that can change abruptly under slight variations in experimental parameters. Unlike conventional BCS superconductors, the HTSCs are not fully theoretically understood, with the nature of the glue enabling Cooper pairing and the origin of the pseudogap state yet to be definitively found, among other many other questions.

A means of better understanding the interactions that enable superconductivity in HTSCs is by performing an ultrafast quench of the superconducting state through the absorption of an intense femtosecond pulse of light, allowing the recovery of superconductivity to be observed without creating an excited steady state. The characteristic timescales of this recovery are thus indicative of the interactions involved.

The majority of literature examining the photoquenching of HTSCs in this manner have been through pump-probe (P-p) experiments, measuring the time-resolved differential reflectivity following the quench and relating that to the dynamics of the quasiparticles photoinjected into the system. While this has unveiled a great deal of further insight into HTSCs, it remains blind to any dependence of the absorption energy in the emitted signal, as well as any changes in the dispersive component of the refractive index.

Here, using Multi-Dimensional Coherent Spectroscopy (MDCS), a fully non-collinear extension of four wave mixing, we are able to examine the changes to both real and imaginary components of the dielectric function during the quench of Bi2212, revealing the dynamics of a response in the dispersive component related to electronic bosons that has been unresolved in P-p measurements. A dependence on absorption energy is also uncovered, which may be related to the resonant absorption by a Lorentz oscillator. These results could serve as a new benchmark for theoretical modelling of the quench and provide insight into the electronic structure of HTSCs.