Photoinduced Ultrafast Phenomena in Correlated Electron Magnets

Photoinduced nonequilibrium phenomena in magnets with strong electron correlation are reviewed. Owing to the strong competition between electron itineracy and localization and the existence of multiple degrees of freedom, a wide variety of drastic changes in electron and lattice structures are brought about by photoirradiation in correlated electron magnets. Recent rapid progress in ultrafast light sources, time-resolved probe techniques, and theoretical calculation methods for the real-time dynamics have promoted studies of photoinduced nonequilibrium dynamics in the systems. We mainly focus on three classes of systems: i) spin–charge coupled magnets where magnetism and electric transport are correlated with each other, ii) correlated electron systems with the spin-state degree of freedom, i.e., multiple spin amplitudes in magnetic ions, and iii) photogenerated carrier dynamics in low-dimensional antiferromagnetic ordered Mott insulating systems. Prototypical target materials in the three classes of systems are manganites, cobaltates, and cuprate superconductors with a perovskite structure, respectively. Recent progress in theoretical studies of the photoinduced phenomena in these systems are reviewed. Experimental results and their theoretical interpretations in terms of the materials are also introduced. Characteristic aspects in comparison with the photoinduced phenomena in conventional magnetic metals and semiconductors are stressed and future perspectives are given.