Berlin 2005 – scientific programme
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M: Metallphysik
M 18: Nanoskalige Materialien I
M 18.6: Talk
Saturday, March 5, 2005, 10:30–10:45, TU H111
Nanocharacterization of magnetoresistant oxide tunnel barrier structures — •Mario Kuduz1, Guido Schmitz2, and Reiner Kirchheim1 — 1Institut für Materialphysik, Universität Göttingen — 2Institut für Materialphysik, Universität Münster
Oxide tunnel barriers (TMR = Tunnel Magneto Resistance) 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.
In this work the nano-structure of TMR devices in as-prepared state also as after annealing at temperatures of 150∘C up to 500∘C using field ion microscopy in combination with a 2D-detection setup was investigated. Spin valve structures consisting of Co and Ni(79) Fe(21) electrodes separated by aluminum-oxide barriers were prepared by ion beam sputter deposition on tips of 30 to 50nm radius of curvature suitable for field ion microscopy (FIM). 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 and the diffusion behavior is discussed in dependence on the annealing temperatures.