Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 37: Symposium Tomographic Methods in Materials Research

M 37.3: Vortrag

Dienstag, 8. März 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.