Giant Magnetic and Optical Anisotropy in Cerium-Substituted M-Type Strontium Hexaferrite Driven by $4f$ Electrons
By performing density-functional calculations, we find a giant magnetocrystalline anisotropy (MCA) constant in abundant element cerium $$\mathrm{Ce}$$ substituted M-type hexaferrite, in the energetically favorable strontium site, assisted by a quantum confined electron transfer from $$\mathrm{Ce}$$ to a specific iron $$\mathrm{2a}$$ site. Remarkably, the calculated electronic structure shows that the electron transfer leads to the formation of $$\mathrm{Ce}^{3+}$$ and $$\mathrm{Fe}^{2+}$$ at the $$\mathrm{2a}$$ site producing an occupied $$\mathrm{Ce}$$$$(4f^1)$ state below the Fermi level that adds a significant contribution to MCA and magnetic moment. A half $$\mathrm{Ce}$$ substitution forms a metallic state, while a full substitution retains the semiconducting state of the strontium hexaferrite (host). In the latter, the band gap is reduced due to the formation of charge-transferred states in the gap region of the host. The optical absorption coefficient shows an enhanced anisotropy between light polarization in parallel and perpendicular directions. Calculated formation energies, including the analysis of probable competing phases, and elastic constants confirm that both compositions are chemically and mechanically stable. With successful synthesis, the $$\mathrm{Ce}$$ hexaferrite can be an alternative high-performing critical-element-free permanent magnet material adapted for use in devices such as automotive traction drive motors.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Materials & Manufacturing Office (AMMTO)
- Grant/Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1994522
- Report Number(s):
- IS-J-11,129
- Journal Information:
- Physical Review Applied, Journal Name: Physical Review Applied Journal Issue: 2 Vol. 20; ISSN 2331-7019
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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