Dependence of carrier doping level on the photo control of (La, Sr)MnO_(3)/SrTiO_(3) functional heterojunction

摘要

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.