Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 22: Spinabh
ängiger Transport I
MA 22.3: Vortrag
Donnerstag, 11. März 2004, 12:45–13:00, H22
GIANT NEGATIVE PHOTOCONDUCTIVITY in La0.7Ca0.3MnO3 THIN FILMS — •Vasily Moshnyaga1, Arnold Giske1, Konrad Samwer1, Elena Mishina2, Takehisa Tamura2, Seiichiro Nakabayashi2, Alexandr Belenchuk3, Oleg Shapoval3, and Leonid Kulyuk3 — 1I. Physikalsiches Institut, Universitaet Goettingen, Tammannstrasse 1, D-37077 Goettingen, Germany — 2Department of Chemistry, Faculty of Science, Saitama University 255 Shimo-okhubo, Saitama, 338-8570, Japan — 3Institute of Applied Physics, Academy of Sciences, Str. Academiei 5, MD-2028 Chisinau, Moldova
The increase of the resistance up to two orders of magnitude under laser illumination (l=760 nm) was observed in La0.7Ca0.3MnO3 (LCMO) epitaxial thin films in ferromagnetic state. Optical absorption also increases by 10-15 procent and the magnetic second harmonic generation (SHG) signal decreases down to zero under the irradiation. The light induced changes are reversible with characteristic relaxation times t 1-30 s. Magnetic field, B=4 T, suppresses the photoconductivity and decreases its relaxation time. Photoinduced effects are caused by the injection of a large number of extra carriers, which change the AFM/FM phase balance in LCMO, favoring the insulating AFM state. Deutsche Forschungsgemeinschaft via SFB, project A2 Goettingen, and the Japanese Society for the Promotion of Science are acknowledged.