Title: Potential high-performance magnet materials: Co- and Al-alloyed Sm 2 Fe 17

Abstract

Sm₂Fe₁₇ has long been known as a potential high-performance magnet whose deficiencies—planar anisotropy and lower-than-optimal T_c—can be remedied by nitrogen addition, but which presents synthesis difficulties. In this work, we apply first-principles calculations to search for alternative low-cost, high-performance permanent magnets in this family, by exploring simultaneous Fe and Al substitution. Specifically, the goal is to improve properties of Sm₂Fe₁₄Al₃ easy-plane magnet at the stoichiometric composition. Density functional theory calculations were executed for three series of compounds, i.e., Sm₂(Fe_1-xCo_x)₁₄Al₃, Sm₂(Fe_1-xCo_x)₁₅Al₂, and Sm₂(Fe_1-xCox)₁₆Al. We find that substitution of Fe with 12–18 of Co in % Sm₂Fe₁₄Al₃ modifies the magnetic anisotropy type from easy plane to easy axis with a substantial anisotropy of 7.1 MJ/m³. We also demonstrate that the largest part of magnetic anisotropy is introduced by 4f Sm atom electrons. Thus the rotation of magnetic moment orientation from $$\langle$$$$1\bar10$$$$\rangle$$ to $$\langle$$111$$\rangle$$ is followed by an increase of the occupied 4f state number and, as a result, the orbital part of the magnetic moment of one of the Sm atoms. This increase of the occupied 4f state number at an energy ~ -4.3 eV results in a significant reduction of band structure energy. The substitution of Fe by Co does not significantly reduce the magnetization of the compound and keeps it slightly above 1 T. This combination of magnetic anisotropy and magnetization makes the compound a promising candidate for a permanent magnet.

Authors:

Samolyuk, German D.  ^[1];

• Search DOE PAGES for author "Samolyuk, German D."
• Search DOE PAGES for ORCID "0000-0001-6877-8255"

Parker, David S.  ^[1]

• Search DOE PAGES for author "Parker, David S."
• Search DOE PAGES for ORCID "0000-0001-6101-1334"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Tue May 31 00:00:00 EDT 2022

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office; USDOE Office of Science (SC)

OSTI Identifier:

1885327

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Materials

Additional Journal Information:

Journal Volume: 6; Journal Issue: 5; Journal ID: ISSN 2475-9953

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; electronic structure; magnetic anisotropy; spin-orbit coupling; transition-metal rare-earth alloys