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MA: Fachverband Magnetismus

MA 57: Posters Magnetism II

MA 57.18: Poster

Donnerstag, 19. März 2020, 15:00–18:00, P3

Investigation of Granular Magnetic Exchange Coupled Nano-Composites — Runbang Shao, Siming Zou, Nitish Jangale, Balati Kuerbanjiang, and •Ulrich Herr — Institut für Funktionelle Nanosysteme, Universität Ulm, Ulm, Deutschland

Exchange coupling of ferromagnetic (FM) nanoparticles (NPs) to antiferromagnets (AF) can increase the coercivity and the stability against superparamagnetic fluctuations. It has potential applications in magnetic data storage and permanent magnets. We have studied nano-composites with FM Co or Ni NPs embedded in AF FeMn or IrMn thin films. After application of a field cooling procedure, exchange bias is observed in these nano-composites at low temperature. We observe a pronounced dependence of the exchange bias on FM volume filling factor. To determine the average size of NPs, the superparamagnetic room-temperature m-H curves of reference samples with FM NPs embedded in non-magnetic Cu films are fitted using a superposition of Langevin functions calculated for varying particle size. The fitted size distribution agrees well with the result obtained by T-SEM analysis of free standing NPs. Blocking temperatures are determined via zero field cooled (ZFC) and field cooled (FC) measurements. The switching field distributions (SFD) of NPs, which are measured by first order reversal curves (FORC), are analyzed to have a better understanding of the magnetic anisotropy. Comparison of the magnetic properties of different nano-composites reveals the influence of the exchange coupling on the magnetic energy landscape.