Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)
MA 13.59: Poster
Dienstag, 24. März 2009, 10:15–13:00, P1A
Ferromagnetic Signals in Nominally Non-magnetic Oxide Single Crystals — •M. Ziese1, A. Setzer1, P. Esquinazi1, D. Spemann2, and A. Poeppl3 — 1Division of Superconductivity and Magnetism — 2Division of Nuclear Solid State Physics — 3Division of Magnetic Resonance of Complex Quantum Solids — Faculty of Physics and Geosciences, University of Leipzig, 04103 Leipzig.
Defect-induced room temperature ferromagnetism in oxide semiconductors has attracted wide research interest in recent years. It appears that ferromagnetic order can be induced either in the bulk, when a narrow impurity band is present, or at the surface due to the lowering of the symmetry. In this work the magnetic properties of MgO, MgAl2O4, SrTiO3, LaAlO3, LSAT and ZnO single crystals were investigated. These crystals show three contributions to the magnetization, namely an intrinsic diamagnetic contribution, a paramagnetic contribution due to various transition metal impurities as well as a ferromagnetic contribution. The latter shows remanent magnetization and coercive field values that are strikingly independent of the actual crystal material. The magnetization data are correlated with results from particle induced X-ray emission and electron paramagnetic resonance spectroscopy. The origin of the ferromagnetic contribution is discussed in three different scenarios: (i) as caused by ferromagnetic impurities, (ii) as related to artifacts of the SQUID magnetometer and (iii) as arising from defect-induced ferromagnetism.