Correlations in rare-earth transition-metal permanent magnets

Authors

Ralph Skomski, University of Nebraska-LincolnFollow
Priyanka Manchanda, University of Nebraska-LincolnFollow
Arti Kashyap, IIT MindiFollow

Date of this Version

2015

Citation

JOURNAL OF APPLIED PHYSICS 117, 17C740 (2015)

Comments

Copyright 2015 Used by permission

Abstract

It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition- metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independentelectron level, the use of a single Slater determinant with broken spin symmetry introduces Hund’s rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDAþU approximations to DFT. By contrast, rareearth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe’s crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.