Temperature-dependent magnetocrystalline anisotropy of rare earth/transition metal permanent magnets from first principles: The light RCo${}_5$ (R=Y, La-Gd) intermetallics

Abstract

Computational design of more efficient rare earth/transition metal (RE-TM) permanent magnets requires accurately calculating the magnetocrystalline anisotropy (MCA) at finite temperature, since this property places an upper bound on the coercivity. Here, we present a first-principles methodology to calculate the MCA of RE-TM magnets which fully accounts for the effects of temperature on the underlying electrons. The itinerant electron TM magnetism is described within the disordered local moment picture, and the localized RE-4f magnetism is described within crystal field theory. We use our model, which is free of adjustable parameters, to calculate the MCA of the RCo${}_5$ (R=Y, La-Gd) magnet family for temperatures 0--600 K. We correctly find a huge uniaxial anisotropy for SmCo${}_5$ (21.3 MJm${}^{-3}$ at 300 K) and two finite temperature spin reorientation transitions for NdCo${}_5$. The calculations also demonstrate dramatic valency effects in CeCo${}_5$ and PrCo${}_5$. Our calculations provide quantitative, first-principles insight into several decades of RE-TM experimental studies.

8 pages, 4 figures

References in corpus (5)

• Prediction of a new efficient permanent magnet SmCoNiFe3
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• Temperature Dependence of Magnetocrystalline Anisotropy in Itinerant Ferromagnets
• Integrated ab initio modelling of atomic order and magnetic anisotropy for rare-earth-free magnet design: effects of alloying additions in $\mathrm{L}{1}_0$ FeNi
• Magnetic properties of Nd6Fe13Cu single crystals
• Lattice dynamics and its effects on magnetocrystalline anisotropy energy of pristine and hole-doped YCo${}_5$ from first principles
• First-principles prediction of phase transition of YCo${}_5$ from self-consistent phonon calculations