Regensburg 2002 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 6: Poster

DF 6.2: Poster

Mittwoch, 13. März 2002, 14:30–18:00, Poster Chemie C

Transmission Electron Microscopy on a New Phase in Sr-Fe-Mo-O Thin Films — •Leonore Wiehl, Nicole Auth, Gerhard Jakob, and Hermann Adrian — Materialwissenschaftliches Forschungszentrum (MWFZ), Institut für Physik, Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany

In spin electronic devices high spin polarization is a desired property. Sr₂FeMoO₆ is proposed as a half metallic material, where only electrons of one spin direction exist at the Fermi energy. It is known [1] to crystallize in an ordered double-perovskite structure with tetragonal symmetry (space group P4₂/m) in the ferrimagnetic phase below the Curie temperature of 385 K and is cubic (Fm3m) above.

Sr₂FeMoO₆ thin films (SFMO) on SrTiO₃ substrate have been prepared by Pulsed Laser Deposition under various pressure and temperature conditions in order to optimize crystal quality and electrical performance. Epitaxial film growth with rocking curve widths <0.05^∘ was achieved at substrate temperatures as low as 590 K. In semiconductor technology low substrate temperatures are required to reduce interdiffusion and oxidation.

Electron diffraction photos and HRTEM images from cross-section specimen were made with a TECNAI F30 electron microscope. The diffraction pattern, taken for several different zone axes, show a new superstructure different from the new phases reported recently [2] for polycrystalline magnetoresistive Sr₂FeMoO₆.

[1] C.Ritter et al., J. Phys.: Condens. Matter 12 (2000) 8295-8308

[2] M.X.Dai et al., Solid State Communications 119 (2001) 377-380