Dresden 2011 – scientific programme

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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 63.24: Poster

Friday, March 18, 2011, 11:00–14:00, P2

Electric, magnetic and THz optical properties of La_1−xCa_xMnO₃ (0.45<x<0.7) and (La_1−yPr_y)_0.33Ca_0.66MnO₃ (0<y<1) thin films — •S. Hühn¹, F. Fischgrabe¹, V. Moshnyaga¹, K. Samwer¹, M. Dressel², L. S. Kadyrov³, A.A. Voronkov³, E.S. Zhukova³, and B.P. Gorshunov³ — ¹I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany — ³A. M. Prokhorov Institute of General Physics, Russian Academy of Science, 119991 Moscow, Russia

Multiferroic behaviour has been paid a lot of attention due to the rich physics and great potential for technological applications. Recent studies indicate a close correlation between charge ordering (CO) and the ferroelectricity. For this reason we investigate La_1−xCa_xMnO₃ (0.45<x<0.7) and (La_1−yPr_y)_0.33Ca_0.66MnO₃ (0<y<1), which both show competing ferromagnetic metallic and charge ordering insulating phases. The films were grown by metalorganic aerosol deposition technique on MgO(100) substrates. D.c. and a.c. transport (f=0−40MHz), magnetization and optical conductivity, in the THz range of the electromagnetic spectrum, were studied as a function of temperature (5−350K) and magnetic field (0−7T). THz spectroscopy provides a clear sign for the CO transition at 220−280 K, depending on Ca-doping x. Moreover an indication for possible ferroelectricity in half-doped LCMO was observed from d.c. and a.c. transport measurements. Financial support via SFB 602 TP A2 is acknowledged.