Neutron powder diffraction study of the anion-deficient La0.70Sr0.30MnO3.00-γ manganites
|Sergei Trukhanov 1, Aleksey Trukhanov 2, Svetlana Zemskova 3, Anatoliy I. Beskrovniy 3, Henryk Szymczak 4|
1. The Joint Institute of Solid State and Semiconductor Physics of NASB, P.Brovki str., 19, Minsk 220072, Belarus
Using powder neutron diffraction method the magnetic structure of the anion-deficient solid solution La0.70Sr0.30MnO3.00-γ (γ = 0.15; 0.20) at different temperatures has been determined. It is established that the magnetic structure changes with oxygen vacancies concentration. For the investigated samples the structural phase transitions have not been detected. The oxygen stoichiometric La0.70Sr0.30MnO3.00 sample is ferromagnet with TC ~ 360 K. At the T = 287 K the spontaneous magnetic moment is MS = 2.92(5) µВ / f. u., whereas at the T = 10 K – MS = 3.53(6) µВ / f. u. The direction of the total magnetic moment is along to . For the anion-deficient La0.70Sr0.30MnO2.85 sample the long-range magnetic ordering is absent for all the investigated temperatures. This sample is spin glass with the freezing temperature Tf ~ 45 K. For the anion-deficient La0.70Sr0.30MnO2.80 sample is detected partial long-range antiferromagnetic ordering at the ~ 10 and ~ 40 K. At the T = 40 K the spontaneous magnetic moment is MS = 0.83(3) µВ / f. u., whereas at the T = 10 K – MS = 0.88(1) µВ / f. u. The direction of the antiferromagnetic exis is along to . The obtained data confirm the theory of the magnetic phase state forming for the Sr-doped anion-deficient manganites. In according to this theory in case of orbital ordering absence the lowering of the coordination of the magnetic ion results to change of the indirect superexchange interactions Mn3+-O-Mn3+ sign from positive to negative. This work was partly supported by Belarus Fund for Basic Research (Project F06R-078).
Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Sergei Trukhanov
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth
Submitted: 2007-01-29 15:54 Revised: 2009-06-07 00:44