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 Karl Franzens University Graz

Graz University of Technology 

New hard magnetic materials and applications: A micromagnetic study
Prof. Dr. Josef Fidler
TU Wien - Institute of Solid State Physics - Advanced Magnetism (Micromagnetics & Magnetic Materials)
17:00 - 18:00 Tuesday 01 April 2014 KFU HS 5.01

The search for new candidates of suitable magnetic materials, structures and their expected behaviour as the reduction or the replacement for rare earth elements in permanent magnets is of great economical and scientific interest. On the basis of density functional theory calculations and numerical finite element micromagnetics we have analysed the limits of crystal anisotropy and shape anisotropy on the optimization of magnetization reversal processes in order to improve the coercive field of advanced hard magnetic materials, such as rare earth (RE) intermetallic compounds RECo5 and RE2Fe14B. Numerical finite element micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation for magnetization reversal have been carried out in order to study the influence of the microstructure on the hysteresis properties. The results of the micromagnetic simulations are compared with high resolution and nanoanalytical TEM investigations of various Nd-Fe-B sintered magnets with different RE content and coercive field, respectively.
Besides the simulations on the rare earth permanent magnet materials we also have performed micromagnetic simulations in order to study the possibility of shape anisotropy effects of packed Fe and Co nanorod structures as candidates for rare earth free permanent magnetic applications. Recent developments in nanoscience enabled the production of the nanostructured systems with dimensions approaching the order of few nanometers.
Tape Technology has continued to advance in past few years by introducing new media materials based on Barium ferrite and increasing the areal storage density. We have studied the influence of the recording behaviour of BaFe12O19 nanoplatelets with a diameter ~15 nm and height ~5 nm as candidates for high density recording.