https://doi.org/10.1140/epjst/e2013-01910-4
Regular Article
Photoinduced phenomena in correlated electron systems with multi-degrees of freedom
1 Department of Physics, Tohoku University, Sendai 980-8578, Japan
2 CREST, Sendai 980-8578, Japan
3 Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
a e-mail: ishihara@cmpt.phys.tohoku.ac.jp
Received:
18
March
2013
Revised:
12
May
2013
Published online:
15
July
2013
Photo-induced electronic dynamics in strongly correlated electron system with spin-charge coupling are studied. Motivated from recent optical pump-probe experiments in perovskite manganites and cobaltites, the double-exchange system and the spin-state transition system are theoretically analyzed. First, we focus on the double-exchange interaction in photo-excited state. The time evolutions for the spin and charge structures are examined as functions of the pump photon amplitudes. In the weak-pumping case, the initial charge-ordered antiferromagnetic insulating state tends to become the ferromagnetic metallic state. On the other hand, in the strong-pumping case, the initial antiferromagnetic correlation and insulating character are enhanced after photoirradiation. This unexpected photo-excited state is detectable by the ultrafast optical measurement. Second, in the spin-state transition system, the two-band Hubbard model is analyzed by the time-dependent mean-field approximation. By introducing photons in the low-spin band insulator, high-spin states are generated through the electron-hole pair annihilation process which is governed by the electron band width. We also take into account the relativistic spin-orbit interaction, and compare the results with and without the spin-orbit interaction.
© EDP Sciences, Springer-Verlag, 2013
