Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 3: Magnetic Materials I
MA 3.11: Talk
Monday, March 26, 2007, 12:45–13:00, H22
High-temperature magnetic order in an aromatic polyimide — Jose Barzola-Quiquia1, •Pablo Esquinazi1, Annette Setzer1, Michael Ziese1, Martin Rothermel2, Daniel Spemann2, and Tilman Butz2 — 1Division of Superconductivity and Magnetism, Institute for Experimental Physics II, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany — 2Division of Nuclear Solid State Physics, Institute for Experimental Physics II, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
We have studied the temperature and magnetic field dependence of the magnetization of polyimide foils in the as-received state, after annealing at temperatures T ≤ 1000C and after proton irradiation. The temperature and field dependence depend strongly on the sample initial, annealing as well as on the irradiation conditions. Added to a diamagnetic signal our results provide clear evidence for ferromagnetism and paramagnetism due to different multiplets contributions. The very low magnetic impurity concentration (below 0.5ppm) cannot explain the observed behavior as well as the ferromagnetic and paramagnetic values. The Curie temperature of the ferromagnetic contribution reaches values of the order 800 K upon annealing. The overall results indicate that metal-free polyimides are interesting objects for basic research with potential applications in the area of magnetism.