Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 18: Postersitzung
M 18.18: Poster
Dienstag, 9. März 2004, 14:30–16:30, Saal C
Investigation of oxide tunnel barriers by atom probe tomography (TAP) — •Mario Kuduz1, Guido Schmitz2, and Reiner Kirchheim1 — 1Institut für Materialphysik, Tammannstr. 1, D-37077 Göttingen, Germany — 2Institut für Materialphysik, Whilhelm-Klemm-Str. 10, D-48149 Münster, Germany
Oxide tunnel barriers (TMR) are currently of interest for application in magnetic sensor and storage devices. Compared to giant magneto resistance (GMR) devices, tunnel barriers are distinguished by an improved effect amplitude and a higher base resistivity, so that they may be used in ’current perpendicular to plane’ arrangements.
We investigated the nano-structure of such TMR devices using field ion microscopy in combination with a 2D-detection setup. Spin valve structures consisting of Co and Ni79Fe21 electrodes and Al2O3 barriers were prepared by sputter deposition on tips of 30 to 50 nm curvature radius suitable for field ion microscopy. In spite of the isolating character of the barrier material, the chemical structure can be reasonably characterized by analytical field ion microscopy. The 3D spatial distribution of the atomic species, in particular the distribution of oxygen, is discussed in dependence on various deposition methods.