Dependence of carrier doping level on the photo control of (La, Sr)MnO3/SrTiO3 functional heterojunction

Abstract
In a junction system which consists of ferromagnetic- ( La 1−x Sr x ) MnO 3 and band insulating- SrTiO 3 , the double exchange ferromagnetism in the (La, Sr)MnO 3 layer was controlled by light irradiation through photocarrier injection form SrTiO 3 . We investigated the dependence of hole doping level (Curie temperature) on the photo control of the (La, Sr)MnO 3 /SrTiO 3 heterojunction. Whereas magnetization and conductivity of the heterojunction with T C of 240 K is strongly reduced, including from metal–insulator transition, by light irradiation, that with T C of 280 K cannot be modulated. This result indicates that phase boundary, between the metallic and insulating region on the ( La 1−x Sr x ) MnO 3 phase diagram, plays an important role in photo carrier control of the functional heterojunction.