Persistent photoinduced magnetization and hole droplets in La0.9Ca0.1MnO3 films -: art. no. 132404

Photoinduced magnetization following a stretched exponential growth with time is observed in La0.9Ca0.1MnO3 films exposed to near infrared light in magnetic fields of B >= 0.1 mT. The magnetic irreversibility observed below 56 K between zero-field-cooled and field-cooled films is strongly influenced by illumination, giving space to a persistent magnetic state with increased ferromagnetic interactions, modified magnetic anisotropy and decrease of the blocking temperature to 5 K. When the illumination and the magnetic field are removed the magnetization of the films decays very slowly after a short period of fast relaxation but recovers the original level when the field is applied again. Such behavior obeys predictions for domain pinning in narrow-wall random-field Ising systems. The results suggest trapping of photogenerated electrons by magnetic disorder while the holes contribute to growth of ferromagnetism in the films.