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Title: Large magnetic anisotropy predicted for rare-earth-free F e 16 - x C o x N 2 alloys

Structures and magnetic properties of Fe 16–xCo xN 2 are studied using adaptive genetic algorithm and first-principles calculations. We show that substituting Fe with Co in Fe 16N 2 with a Co/Fe ratio ≤1 can greatly improve the magnetic anisotropy of the material. The magnetocrystalline anisotropy energy from first-principles calculations reaches 3.18 MJ/m 3 (245.6 μeV per metal atom) for Fe 12Co 4N 2, much larger than that of Fe 16N 2, and is one of the largest among the reported rare-earth-free magnets. From our systematic crystal structure searches, we show that there is a structure transition from tetragonal Fe 16N 2 to cubic Co 16N 2 in Fe 16–xCo xN 2 as the Co concentration increases, which can be well explained by electron counting analysis. As a result, different magnetic properties between the Fe-rich (x ≤ 8) and Co-rich (x > 8) Fe 16–xCo xN 2 is closely related to the structural transition.
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9202
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1701093
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 22; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1347745
Alternate Identifier(s):
OSTI ID: 1337439