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MA: Magnetismus
MA 5: Spinstrukturen und magnetische Phasenüberg
änge
MA 5.8: Vortrag
Freitag, 4. März 2005, 12:15–12:30, TU EMH225
Substitution of Manganese in electron-doped manganites — •Uwe Amann1,2, Clemens Ritter2, Dietmar Hohlwein1,3, and Jörg Ihringer1 — 1Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany — 2Institut Laue-Langevin, 6, Rue Jules Horowitz, B.P. 156, 38042 Grenoble, France — 3Hahn-Meitner-Institut, Glienicker Straße 100, 14109 Berlin, Germany
As part of a systematic investigation[1,2,3] of substitution effects of Manganese by other trivalent atoms, we investigated the temperature-dependant evolution of the magnetic moments in the CMR-compound Y0.1Ca0.9Ga1−xMnxO3 for x = 0.0, 0.02, 0.04.
For temperatures above the Neel temperature the samples display monophase Pnma structure. With the onset of magnetic ordering, the system splits into at least two phases, an antiferromagnetic G-type ordered matrix into which ferromagnetic regions (FM) are embedded and a second, monoclinic antiferromagnetic (M-AFM) phase in nuclear space group P21/m.
Substitution with different ions acts differently on the magnetic structure: Iron inhibits the formation of FM and M-AFM phases, but doesn’t disturb the magnetic exchange paths, so there is no change in phase transition temperature. Gallium on the other hand, without magnetic moment, disturbs the exchange paths, shifting the phase transition to lower temperatures.
[1]Th. Lottermoser, Nature 430 (2004), 541-544.
[2]U. Amann et al., Z. Krist, Suppl. 18 (2000), 79
[3]K. Hagdorn et al.,Eur. Phys. J. B, 11 (1999), 243