Research Projects

Accelerating progress in wireless communication and the emerging frontiers of 6G and quantum information processing are driving a critical demand for miniaturized, low-power, high-frequency nonreciprocal components. The sub-terahertz regime (100–300 GHz) is poised to play a transformative role in future communication and sensing technologies. Nonetheless, the functional deployment of nonreciprocal devices remains hindered by the limitations of existing magnetic materials, which include excessive damping, low FMR thresholds, thermal unreliability, and poor integration compatibility. This proposal seeks to address these challenges by developing high-quality epitaxial thin films of doped strontium hexaferrite (SrF), characterized by strong magnetocrystalline anisotropy and inherent suitability for high-frequency applications. This project is centered on tailoring the magnetic properties of SrF-based epitaxial films such as high FMR frequency, reduced damping, and anisotropy directionality through the synergistic application of controlled doping and strain engineering techniques. The films will be deposited via PLD on carefully selected lattice-matched substrates to promote phase purity and oriented growth. The structure–property correlations will be systematically investigated through a suite of techniques, including XRD, AFM, TEM, SQUID magnetometry, and broadband VNA-based FMR measurements. Elemental substitutions involving Ba²⁺ and Ca²⁺ at the Sr²⁺ site, along with Y³⁺ and In³⁺ at the Fe³⁺ site, will be systematically explored to tune the local electronic structure, manipulate magnetic anisotropy, and mitigate relaxation losses, crucial for achieving sub-THz operational efficacy. The distinguishing feature of this research lies in its synergistic approach, wherein theoretical and computational modeling, specifically time-dependent density functional theory and many-body perturbation theory, will be employed alongside experimental investigation to construct a predictive structure–property paradigm. The outcomes of these studies will shed light on the fundamental mechanisms underlying magnetic damping, exchange interactions, and anisotropy, offering critical guidance for tuning material composition and refining growth conditions. Complementary full-wave electromagnetic simulations (CST, COMSOL) will be conducted to guide the design and optimization of miniaturized devices, informed by experimentally extracted magnetic parameters. The project will culminate in the fabrication and performance validation of an integrated sub-THz nonreciprocal device employing the engineered SrF films. Device performance encompassing transmission efficiency, isolation characteristics, and modulation response will be systematically evaluated under varying magnetic field strengths, dopant concentrations, and structural layouts. A successful demonstration will serve as a proof-of-concept for the on-chip platforms for future sub-THz technologies.