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Large magnetic anisotropy in Co-Fe-Ni-N ordered structures: a first-principles study.
1Department of Physics, National Institute of Technology Nagaland, Dimapur, Nagaland-797103, India.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|December 17, 2021
Summary
Researchers explored rare-earth-free permanent magnets, focusing on cobalt-iron-nickel structures with nitrogen doping. They achieved enhanced magnetic anisotropy, crucial for developing efficient and affordable permanent magnets.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Materials Science
Background:
- Developing rare-earth-free permanent magnets (PMs) necessitates precise control over intrinsic magnetic properties: saturation magnetization (μ₀Ms), uniaxial magnetic anisotropy (Ku), and Curie temperature (TC).
- Existing PMs often rely on rare-earth elements, posing environmental and cost concerns, driving research into alternative materials.
- Tailoring these properties is key to bridging the performance gap between inexpensive ferrite magnets and high-performance neodymium-iron-boron (Nd-Fe-B) magnets.
Purpose of the Study:
- To investigate the intrinsic magnetic properties of CoₓFe₁₋ₓNi and CoₓFe₁₋ₓNiN₀.₂₅ ordered structures.
- To analyze the potential of these materials for rare-earth-free permanent magnet applications.
- To understand the underlying mechanisms responsible for enhanced magnetic anisotropy.
Main Methods:
- First-principles electronic structure calculations were employed to analyze magnetic properties.
- Perturbation theory was utilized to detail the contributions to magnetic anisotropy.
- Systematic investigation of cobalt-iron-nickel alloys with and without nitrogen doping.
Main Results:
- Predicted enhanced structural stability and significantly improved uniaxial magnetic anisotropy (Ku) in CoₓFe₁₋ₓNiN₀.₂₅ structures, with values ranging from 1.53–2.29 MJ m⁻³.
- Identified CoNiN₀.₂₅ as an exception, exhibiting planar anisotropy.
- Attributed the large predicted Ku to the combined effects of increased tetragonal distortion and induced orbital distortion from Co substitution and interstitial N-doping.
Conclusions:
- The study demonstrates that simultaneous Co substitution and interstitial N-doping in Co-Fe-Ni systems can effectively enhance magnetic anisotropy.
- These findings suggest a viable pathway for designing efficient and affordable rare-earth-free permanent magnets.
- Tailoring magnetic anisotropy through controlled doping and structural modifications is crucial for advancing permanent magnet technology.
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