Berlin 2005 – scientific programme
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M: Metallphysik
M 37: Symposium Tomographic Methods in Materials Research
M 37.3: Talk
Tuesday, March 8, 2005, 11:40–12:00, TU H1058
Tomographic characterization of magnetic sensor materials — •Guido Schmitz1, Constantin Ene2, and Mario Kuduz2 — 1Institut für Materialphysik, Westf. Wilhelms-Univ., Wilhelm-Klemm-Str. 10, 48149 Münster, Germany — 2Institut für Materialphysik, Univ. Göttingen, Friedrich-Hundt-Platz 1, 37077 Göttingen, Germany
Atomprobe tomography provides a 3D local chemical analysis with atomic sensitivity. Due to the 3D chemical information, atomic transport processes can be determined even in complex nanocrystalline materials. The application of the method to thin film multilayers is demonstrated at the example of magneto resistive sensor devices. Investigations of {NiFe/Cu/Co/Cu}, {Cu/Py}, {Co/Al2O3/NiFe} systems are presented. These structure are severely unstable from a thermodynamic point of view, so that their thermal stability and reaction gets an important issue for any technical application. Based on the 3D volume reconstruction, different mechanisms of atomic transport are identified and their relative importance for the degeneration of the giant magneto resistance effect or the electrical stability of tunnel barriers determined. According to the nano-analysis, volume diffusion induced by non-equilibrium point defects seems to be the dominant factor in GMR systems. In oxide tunnel barriers, a thermal treatment leads to zones of local enrichment of metallic impurities, which probably induces electrical breakthroughs.