Regensburg 2013 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 12: Poster 1
DF 12.34: Poster
Dienstag, 12. März 2013, 10:30–13:30, Poster D
Enhanced anisotropy of Ni nanoparticles embedded in IrMn matrices — •Balati Kuerbanjiang1, Ulf Wiedwald2, Felix Häring2, Johannes Biskupek3, Ute Kaiser3, and Ulrich Herr1 — 1Inst. of Micro and Nanomaterials, Ulm University, 89081 Ulm — 2Inst. of Solid State Physics, Ulm University, 89069 Ulm — 3Electron Microscopy Group of Materials Science, Ulm University, 89081 Ulm
Magnetic nanoparticles have huge potential in future applications such as data storage, nanosensors and biomedicals. However, superparamagnetic effect puts a limit on the minimum size of the particles in terms of usage. One way to overcome this limit is attaining exchange anisotropy by coupling the ferromagnetic (FM) particles to an antiferromagnetic (AFM) media. Different from most of the literature works, we developed a sample preparation system where we can independently change the type of FM and AFM materials, allowing us to study the effect in a flexible way. In this work, we have produced Ni nanoparticles using plasma gas condensation technique and in-situ embedded them in an IrMn matrix. We show that the embedded Ni nanoparticles display enhanced coercivity Hc and exchange bias Hex. Furthermore, we find that the effect is stronger in smaller particles, and the extracted exchange energy values are in the range of the values found in FM/IrMn bilayer systems. The particle size dependencies of Hc and Hex have been measured in detail, and we propose a micromagnetic model to describe the observed trends. By conducting FC/ZFC measurements, we show a clear increase of blocking temperature for embedded particles compared to identical non-embedded particles.