Unlocking 6G Potential: Chromium-Substituted Hexaferrites with Record Coercivity

Research Highlight Materials Horizons 2025

The Scientific Challenge

While strontium hexaferrites are widely used as hard magnets, tuning their properties for high-frequency applications often compromises their magnetic hardness. Our goal was to achieve a precise substitution of iron with chromium to enhance both coercivity and resonance frequency without losing phase purity. \mathtm{} $Cr_{3}$

The Innovation: Anomalous X-ray Diffraction

To understand the mechanism, we employed Anomalous X-ray Diffraction (AXRD) at the Swiss Light Source synchrotron. This advanced technique allowed us to distinguish between Fe and Cr atoms — which have nearly identical scattering factors — and map their exact distribution across five different crystallographic sites.

Key Findings

• Record Performance: We achieved a significant boost in coercive force, reaching 13.9 kOe, and a natural ferromagnetic resonance (NFMR) frequency of 129 GHz.
• Selective Occupation: AXRD revealed that $Cr^{3+}$ ions selectively occupy octahedral sites (2a, 12k, and $4f_2$), which is the key to increasing the anisotropy field.
• 6G Applications: These submicron particles are ideal candidates for rare-earth-free permanent magnets and sub-terahertz spintronic devices needed for 6G wireless networks.

“Chromium substitution offers a unique advantage: it provides narrower resonance lines compared to aluminum, making it superior for high-efficiency terahertz electronics.”

Citation Info

@article{gorbachev2025submicron,
  title={Submicron particles of Cr-substituted strontium hexaferrite: anomalous X-ray diffraction studies, hard magnetic properties, millimeter-wave absorption, and research prospects},
  author={Gorbachev, Evgeny A and Lebedev, Vasily A and Kozlyakova, Ekaterina S and Alyabyeva, Liudmila N and others},
  journal={Materials Horizons},
  volume={12},
  pages={5893--5907},
  year={2025},
  publisher={Royal Society of Chemistry}
}