Ultrafast optical and far-infrared quasiparticle dynamics in correlated electronmaterials

Abstract

We review the application of ultrafast optical spectroscopy in the study ofcorrelated electron materials. The emphasis is on all-optical pump–probe andoptical pump–far-infrared probe experiments on (a) colossal-magnetoresistancemanganites and (b) high-temperature superconductors. The experimentaltechniques are discussed followed by a brief review of ultrafast electrondynamics in conventional wide-band metals which serves as a starting point inunderstanding the dynamics in more complex metallic systems. In thehalf-metallic manganites, the quasiparticle dynamics in the ferromagnetic metallicstate can be understood in terms of a dynamic transfer of spectral weight which isinfluenced by the lattice and spin degrees of freedom. For the high-temperaturesuperconductors, ultrafast quasiparticle dynamics are sensitive to the orderparameter and superconducting pair recovery occurs on a picosecond timescale.These results show that, in general, ultrafast optical spectroscopy provides asensitive method to probe the dynamics of quasiparticles at the Fermi level.