Lattice correlation of Hubbard excitons in a Mott insulator Sr2IrO4 and reconstruction of their hopping dynamics via time-dependent coherence analysis of the Bragg diffraction

TL;DR

This paper reveals strong lattice coupling of Hubbard excitons in Sr2IrO4 and reconstructs their hopping dynamics using time-dependent coherence analysis of Bragg diffraction, highlighting complex quasiparticle behavior in correlated oxides.

Contribution

It introduces a novel coherence analysis method to map quasiparticle diffusion and uncovers unexpected strong lattice coupling of excitons in Sr2IrO4.

Findings

Strong lattice coupling of Hubbard excitons observed

Reconstructed spatiotemporal quasiparticle diffusion maps

Method applicable to oxide heterostructure characterization

Abstract

In correlated oxides the coupling of quasiparticles to other degrees of freedom such as spin and lattice plays critical roles in the emergence of symmetry-breaking quantum ordered states such as high temperature superconductivity. We report a strong lattice coupling of photon induced Hubbard excitonic quasiparticles in spin-orbital coupling Mott insulator Sr2IrO4. Combining time-resolved optical spectroscopy techniques, we further reconstructed spatiotemporal map of the diffusion of quasiparticles via time-dependent coherence analysis of the x-ray Bragg diffraction peak. Due to the unique electronic configuration of the exciton, the strong lattice correlation is unexpected but extends the similarity between Sr2IrO4 and cuprates under highly non-equilibrium conditions. The coherence analysis method we developed may have important implications for characterizing the structure and carrier dynamics in a wider group of oxide heterostructures.