Regensburg 2000 – wissenschaftliches Programm
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AM: Magnetismus
AM 14: Magnetowiderstand I: Manganate
AM 14.8: Vortrag
Mittwoch, 29. März 2000, 16:00–16:15, H10
Microstructure and Magnetotransport in Manganite Films Prepared by Metalorganic Aerosol Deposition — •Vasily Moshnyaga1, Stefan Klimm1, Reinhard Tidecks1, Siegfried Horn1, and Konrad Samwer2 — 1Institut für Physik, Universität Augsburg, Universitätsstr.1, 86159 Augsburg — 21. Physikalisches Institut, Universität Göttingen, Bunsenstr. 9, 37073 Göttingen
Epitaxial thin films of La-(Ca,Sr)-Mn-O manganite oxides were grown on MgO (100) substrates by metalorganic aerosol deposition (MAD) technique and analyzed by X-ray diffraction and atomic force microscopy. Electrical transport measurements were carried out in the range of temperatures T=4.2-350 K, magnetic fields B=0-12 T and external hydrostatic pressure p=0-16 kbar. An intra-grain spin polarized magnetoresistance (MR) (enhanced low-field MR and a broad temperature distribution of MR) was found in epitaxial LCMO thin films. Magnetotransport characteristics (metal-insulator transition temperature and maximal MR-values) correlate well with a disorder induced modification of the film microstructure on the scale of 10-40 nm, that is significantly smaller than the crystalline grain size (200-500 nm). Extrinsic pressure effect at p=8-16 kbar, resulting in an increase of the film resistivity of up to 3 orders of magnitude at low temperatures, was found in films with extraordinary large values of the pressure coefficient of the metal-insulator transition temperature. The possibility to control magnetotransport by tuning the film microstructure by means of processing conditions as well as by an external pressure is proposed.