Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 2: Micro and Nanostructured Magnetic Materials I
MA 2.1: Vortrag
Montag, 25. Februar 2008, 10:15–10:30, EB 301
Interaction effects in Fe nanoparticle/permalloy thin-film hybrid systems — •Jens Müller1,2, Yongqing Li1,3, Stephan von Molnár1, and Steffen Wirth2 — 1Florida State University, Tallahassee, USA — 2MPI-CPfS Dresden — 3MPI-FKF Stuttgart
Elongated magnetic nanoparticles attract continuing attention in view of potential technological applications in data storage or spintronics. Using gated Hall magnetometers made from GaAs/AlGaAs 2DEG heterostructures we recently demonstrated a moment sensitivity of 104 µB by measuring the switching of a single magnetic Fe particle. Particles of 5 - 15 nm in diameter and generally 80 - 250 nm in height may be grown by STM-assisted CVD, an advantageous technique for exact positioning of individual Fe particles on different substrate materials.
The investigation of such nanoparticles is not only driven by the quest for a more detailed picture of the magnetization behavior of the particles themselves but ultimately to apply these small and local magnetic flux sources to intentionally influence and investigate other materials. A first step in this direction is to study hybrid systems of magnetic particles and an underlying magnetic film. Growing arrays or individual particles onto a permalloy thin film strongly enhances interactions between adjacent particles.
Also, the particles alter the magnetic domain structure of the magnetic thin film making its transport properties sensitive to the magnetization state of the particle array grown on top. We find and discuss a distinct (negative) switching effect in the magnetoresistance that persists up to room temperature.