Enhancement of Photoinduced Effects in Annealed Bi$_{1-x}$Ca$_{x}$MnO$_{3 }$Thin Films.*

Doped rare-earth manganese oxides (manganites) exhibit a rich variety of interesting physical phenomena including their sensitivity to application of magnetic, electric fields, and electromagnetic wave irradiation. A photoinduced insulator to conductor transition in charge-ordered (CO) manganites is especially interesting from the point of view of creating photonic devices. Thin films of Bi$_{0.4}$Ca$_{0.6}$MnO$_{3}$ exhibit large photoinduced effects associated with melting of the charge ordering by visible light and can support conducting and insulating phase coexistence on a submicron scale [1]. We have found significant increase of the photoinduced resistivity changes and the life time of the photoinduced conducting phase after annealing. The changes in current-induced effects in annealed films will be also reported, and the possible origin of these effects will be discussed. [1] V. N. Smolyaninova at al., Phys. Rev. B 76, 104423 (2007).