Effect of illumination on magnetization and microwave absorption of La1-xCaxMnO3 (x < 0.2) films

: Huhtinen H, Laiho R, Vlasenko LS, Vlasenko MP, Zakhvalinskii V, Leiro J, Mattila S, Sutara F, Vondracek M

Publisher: ELSEVIER SCIENCE BV

: 2008

Journal of Magnetism and Magnetic Materials

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

: J MAGN MAGN MATER

: 320

: 11

: 1747

: 1752

: 6

: 0304-8853

DOI: https://doi.org/10.1016/j.jmmm.2008.01.038

Light-induced changes of the hysteresis loops of magnetization and microwave absorption are investigated in low-doped La1-xCaxMnO3 (x<0.2) thin films. The width of the hysteresis loops decreases clearly under illumination with visible or near-infrared light at temperatures below 50 K. The microwave conductivity has a minimum value at magnetic fields corresponding to the magnetization reversal and is shifted towards weaker fields under illumination. These effects show complex nonexponential time evolution and dependence on strength of the magnetic field. The results can be explained by assuming that small ferromagnetic metallic regions exist within the insulating ferromagnetic phase of the sample, and that these regions are expanded by optically induced charge transfer between Jahn-Teller split e(g) states of neighboring Mn3+ ions. Decrease of the Mn3+ XPS core level spectrum is observed in the samples under illumination with a HeNe laser. (C) 2008 Elsevier B.V. All rights reserved.