Exploring doped strontium hexaferrite through micromagnetics for sub-terahertz applications

Abstract The growing demand for high-speed, low-latency communication in the Internet of Things era is accelerating research into terahertz (THz) technologies (100 GHz–10 THz). Strontium Hexaferrite (SrFe 12 O 19 or SrF) and its substituted variants show great potential for sub-terahertz applications due to their ability to exhibit natural ferromagnetic resonance (NFMR) without external magnetic fields. In this study, we employ micromagnetic modeling to investigate the resonance behavior of doped SrF focusing on key magnetic parameters such as saturation magnetization ( M s ) and magnetic anisotropy constant ( K 1 ). Notably, co-doping with Y 3+ –Al 3+ and Ca 2+ –Al 3+ boosts the resonance frequency up to 206 GHz and 181 GHz, respectively. Furthermore, our simulation results reveal field-dependent tunability, with the resonance frequency reaching 350 GHz under a +5T bias and dropping to 40 GHz under −5T. The resulting trends establish a strong correlation between FMR frequency and intrinsic magnetic parameters M s and K 1 , offering a predictive framework for designing hexaferrite-based materials. The combined use of compositional engineering and magnetic field control presents a flexible strategy for developing advanced materials for high-frequency communication, radar, and spintronic technologies. While the present findings are based on micromagnetic simulations, they offer a valuable predictive framework that lays the foundation for future experimental validation to assess real-world applicability and device performance.