Regensburg 2016 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Topical session: Integrated computational materials engineering for design of new materials III

MM 11.3: Talk

Monday, March 7, 2016, 16:30–16:45, H39

Theoretical screening of 1-12 and 1-12-X phases on the search for new hard-magnetic compounds with low rare-earth content — Wolfgang Körner, •Georg Krugel, Daniel F. Urban und Christian Elsässer — Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstr. 11, 79108 Freiburg, Germany

The ThMn₁₂-type crystal structure recently attracted renewed experimental and theoretical interest as being a promising starting point in the search for new hard-magnetic compounds with low rare-earth content. This is mainly due to the atomic rare-earth to transition-metal ratio of 1:12 and the tetragonal crystal symmetry which is necessary for high magnetocrystalline anisotropy. Estimates of the energy product (BH)_max for NdFe₁₂N yield about 686 kJ/m³ which even exceeds the best available hard magnet nowadays, namely Nd₂Fe₁₄B with (BH)_max=516 kJ/m³.

We report on theoretical investigations, by means of density functional theory, of the 1-12 and 1-12-X phases derived from the known ThMn₁₂-type structure. We have extended our computational high-throughput screening (HTS) approach [1] by approximate evaluations of the anisotropy constant K₁, the anisotropy field H_a and an estimate of (BH)_max. Our calculation of K₁ is fast since it is based on the crystal field parameters and avoids expensive total-energy calculations. Besides NdFe₁₂N which has the highest magnetization, several 1-12 and 1-12-X compounds based on Ce instead of Nd are presented which are interesting alternative hard-magnetic compounds.

[1] N. Drebov et al, New J. of Phys. 15, 125023 (2013)