Strong lattice correlation of non-equilibrium quasiparticles in a pseudospin-1/2 Mott insulator Sr(2)IrO(4)

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 quasiparticles in spin-orbital coupling Mott insulator Sr(2)IrO(4) probed via optical excitation. Combining time-resolved x-ray diffraction and optical spectroscopy techniques, we reconstruct a spatiotemporal map of the diffusion of these quasiparticles. Due to the unique electronic configuration of the quasiparticles, the strong lattice correlation is unexpected but extends the similarity between Sr(2)IrO(4) and cuprates to a new dimension of electron-phonon coupling which persists under highly non-equilibrium conditions.