Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.59: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

AC electric transport in CMR-manganite thin films — •Florian Fischgrabe, Sebastian Hühn, Jon-Olaf Krisponeit, Konrad Samwer, and Vasily Moshnyaga — I. Physikalisches Institut, Göttingen

We report ac measurements on (La_0.6Pr_0.4)_0.7Ca_0.3MnO₃ and La_1−xCa_xMnO₃ thin films prepared by metalorganic aerosol deposition technique. The measurements were carried out for temperatures, T=10-300 K, frequencies, f=10 Hz-1 MHz and applied magnetic field ,B=0-1 T,to get a detailed view on the electric properties close to the phase transition. While the dc resistance as a function of temperature shows a well-known metal-insulator-transition behaviour, the other features appear when varying frequency. The imaginary part of the impedance demonstrates a strong phase shift near the metal insulator transition and even changes its sign directly after the metal insulator transition. Furthermore in a half-doped LaCaMnO₃ (x≈ 0.5) we observed a pronounced difference between ac and dc measurements for temperatures T<100 K. The influence of FM/AFM coexistence as well as of charge ordering on the ac electric transport will be discussed.