Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 3: Magnetic Heuslers, Half-metals and Oxides (jointly with TT)

MA 3.6: Talk

Monday, March 16, 2015, 10:45–11:00, H 0112

Mn-based candidates for rare earth free permanent magnet — •Adel Kalache, Bayardulam Jamiyansuren, Siham Ouardi, Guido Kreiner, and Claudia Felser — Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

Permanent magnets are used in a wide range of applications from hybrid cars and wind turbines to computer hard-disk drives. Rare earth (RE) magnets such as Nd-Fe-B and Sm-Co show unique hard magnetic performance but are subject to both price and supply issues. New RE free permanent magnets are also needed to fill the gap between the low cost hexagonal ferrites and the expensive RE magnets. Some Mn-based intermetallic compounds are promising candidates because of their high Curie temperature and their tetragonal structure of the L1₀ type or distorted Heusler D0₂₂ type. The resulting intrinsic uniaxial magnetic anisotropy leads to appreciable hard magnetic properties. The synthesis of Mn-based RE free magnets with melt spinning technique improves some extrinsic properties such as microstructure and grain size. These features allow an increase of the coercivity of material, leading to higher figure of merit BH_max. Structural characterization and magnetic properties of some tetragonal Mn-based compounds such as Mn-Ga and Mn-Ge will be presented. Neutron diffraction is reported for Mn₆₀Ga₄₀. Substitution of Mn with other transition metals will also be discussed in order to improve the magnetic hardness.