Photocarrier injection effect on double exchange ferromagnetism in (La, Sr)MnO3/SrTiO3 heterostructure

We have fabricated a (La1-xSrx) MnO3/SrTiO3 heterostructure and measured the temperature dependence of magnetization and resistivity under white light irradiation. We found that increased resistivity and a decrease of the metal-to-insulator transition temperature by 10 K occur under illumination of light at a wavelength below 400 nm. In particular, an additional photoinduced metal-semiconductor transition is observed below 100 K with decreased magnetization. This behavior can be explained by considering that the hole concentration in the (La1-xSrx) MnO3 layer decreases owing to electron injection following the photoexcitation of SrTiO3. We also confirmed electron injection along a perpendicular direction to the heterostructure using current-voltage measurement. (C) 2000 American Institute of Physics. [S0003-6951(00)00322-3].