Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 25: Poster Session

MM 25.40: Poster

Mittwoch, 29. März 2006, 15:30–17:30, P4

Investigation on structure and magnetic properties of La1-xSrxMnO3 — •Haifeng Li, Yixi Su, Jörg Perßon , Paul Meuffels, Jens Walter, Rolf Skowronek, and Thomas Brückel — Institute for Solid State Research, Research Center Jülich, D-52425 Jülich, Germany

Transition metal oxides (TMO) have attracted strong attention since the interesting phase diagrams and unusual properties are expected depending on the interplay of lattice, spin, charge and orbital degrees of freedom. It has been realized the physical properties and the ground states of TMO are very sensitive to the synthesis conditions. In this poster, we report the optimization of powder preparation and single crystal growth of La1-xSrxMnO3. Structural and magnetic properties of air sintered, Ar and O2 annealed La7/8Sr1/8Mn1-γO3+δ have been systematically studied by neutron and X-ray powder diffraction and SQUID. [1] The possibilities of Mn deficiency after annealings and the sources of excess oxygen are studied. The correlation between both decreases of mean Mn-O and La (Sr)-O bond lengths and the increase of oxygen indicates excess oxygen is a superficies of cation vacancies. The ZFC magnetization of Ar annealed sample shows signatures of the reported structural transitions. The decrease of Tc after annealings is due to decrease of total strength of magnetic interaction, increase of magnetization coefficient B of spin wave, decrease of numbers of nearest magnetic neighbors and discontinuously increase of actual percentage of Mn site vacancies. The trace of Mn2+ is detected by XPS, indicating the possible existence of ligand hole states at oxygen. [1] H. F. Li, et al. (submitted)