Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy

Abstract Density functional theory (DFT) and its extensions, such as DFT+U and DFT+dynamical mean-field theory, are invaluable for studying magnetic properties in solids. However, rare-earth (R) materials remain challenging due to self-interaction errors and the lack of proper orbital polarization....

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Main Authors: Y. Lee, Z. Ning, R. Flint, R. J. McQueeney, I. I. Mazin, Liqin Ke
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:npj Computational Materials
Online Access:https://doi.org/10.1038/s41524-025-01632-3
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author Y. Lee
Z. Ning
R. Flint
R. J. McQueeney
I. I. Mazin
Liqin Ke
author_facet Y. Lee
Z. Ning
R. Flint
R. J. McQueeney
I. I. Mazin
Liqin Ke
author_sort Y. Lee
collection DOAJ
description Abstract Density functional theory (DFT) and its extensions, such as DFT+U and DFT+dynamical mean-field theory, are invaluable for studying magnetic properties in solids. However, rare-earth (R) materials remain challenging due to self-interaction errors and the lack of proper orbital polarization. We show how the orbital dependence of self-interaction error contradicts Hund’s rules and plagues magnetocrystalline anisotropy (MA) calculations, and how analyzing DFT states that respect Hund’s rules can mitigate this issue. We benchmark MA in RCo5, R 2Fe14B, and RFe12, extending prior work on RMn6Sn6, achieving excellent agreement with experiments. Additionally, we illustrate a semi-analytical perturbation approach that treats crystal fields as a perturbation in the large spin-orbit coupling limit. Using Gd-4f crystal-field splitting, this method provides a microscopic understanding of MA and enables rapid screening of high-MA materials.
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spelling doaj-art-cbdcb00ecec44fb2bf7b1ec910347eac2025-08-20T03:26:47ZengNature Portfolionpj Computational Materials2057-39602025-06-0111111110.1038/s41524-025-01632-3Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropyY. Lee0Z. Ning1R. Flint2R. J. McQueeney3I. I. Mazin4Liqin Ke5Ames National Laboratory, U.S. Department of EnergyAmes National Laboratory, U.S. Department of EnergyAmes National Laboratory, U.S. Department of EnergyAmes National Laboratory, U.S. Department of EnergyDepartment of Physics and Astronomy, George Mason UniversityAmes National Laboratory, U.S. Department of EnergyAbstract Density functional theory (DFT) and its extensions, such as DFT+U and DFT+dynamical mean-field theory, are invaluable for studying magnetic properties in solids. However, rare-earth (R) materials remain challenging due to self-interaction errors and the lack of proper orbital polarization. We show how the orbital dependence of self-interaction error contradicts Hund’s rules and plagues magnetocrystalline anisotropy (MA) calculations, and how analyzing DFT states that respect Hund’s rules can mitigate this issue. We benchmark MA in RCo5, R 2Fe14B, and RFe12, extending prior work on RMn6Sn6, achieving excellent agreement with experiments. Additionally, we illustrate a semi-analytical perturbation approach that treats crystal fields as a perturbation in the large spin-orbit coupling limit. Using Gd-4f crystal-field splitting, this method provides a microscopic understanding of MA and enables rapid screening of high-MA materials.https://doi.org/10.1038/s41524-025-01632-3
spellingShingle Y. Lee
Z. Ning
R. Flint
R. J. McQueeney
I. I. Mazin
Liqin Ke
Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
npj Computational Materials
title Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
title_full Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
title_fullStr Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
title_full_unstemmed Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
title_short Importance of enforcing Hund’s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
title_sort importance of enforcing hund s rules in density functional theory calculations of rare earth magnetocrystalline anisotropy
url https://doi.org/10.1038/s41524-025-01632-3
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