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Aluminium-doped magnesium ferrite (MAFO) has garnered significant interest due to its recently observed low microwave loss properties, making it invaluable for applications at high-frequency operations, including fields like spintronics and magnonics. This study delves into the optical and dielectric properties of MgAl0.5Fe1.5O4 synthesized via a conventional solid-state method followed by sintering at 1350 °C for 6 hrs. The X-ray diffraction analysis confirmed the formation of pure, single-phase MAFO spinel ferrite with the lattice constant of 8.313 Å. The Williamson–Hall (W-H) method was employed to determine the crystallite size and strain from X-ray diffraction data, resulting in values of 115.4 nm and 9.37 × 10–4, respectively. UV–visible spectroscopy was used to determine the optical properties, revealing a band gap of 2.38 eV and an average refractive index of 2.09 for the investigated spinel ferrite. The dielectric properties including capacitance, dielectric constant (ε), dielectric loss, ac conductivity, complex impedance, and modulus of MAFO sample were studied as a function of frequency for various temperatures. This comprehensive analysis sheds light on the previously undiscovered traits in the material's transport phenomena and optical attributes, opening an exciting and active field of research into its other physical properties.

This study presents a planar hybrid system consisting of an electric-field-coupled resonator (ELCR) and yttrium iron garnet (YIG) film, designed to investigate the interaction between photons and magnons at room temperature. This hybrid system has been designed and simulated using the commercial electromagnetic full-wave simulator CST Microwave Studio. The phenomenon of anti-crossing between the photon mode of the ELCR and the magnon modes of the YIG was observed by analyzing the |S21|-versus-frequency spectrum under varying strengths of bias magnetic fields. We present a comprehensive theoretical framework that explains the observed anti-crossing effect resulting from photon-magnon coupling (PMC) and provide estimations for the strength of PMC (Δ). Additionally, the interaction between photons and magnons was manipulated through two distinct methods: by adjusting the thickness (tYIG) of the YIG film and by positioning the YIG films along the microstripline. For the ELCR (for tYIG = 25 μm), Δ comes to 58 MHz, while changing tYIG from 2 μm to 50 μm, enabling more precise control of the Δ parameter across the span of 17 MHz to 84 MHz. Similarly, the YIG positioning at a different location along the microstripline allowed manipulation of Δ from 5 to 50 MHz. The resultant PMC can be significantly tuned by 400% to 900% in a planar-geometry ELCR-YIG hybrid system. This research offers avenues for developing innovative hybrid systems that afford greater control over the magnitude of PMC in a planar configuration, representing a promising direction for future advancements in hybrid magnonic systems.

Magnetic garnets, a diverse group of magnetic insulating materials, have been the subject of extensive research for decades, owing to their versatility and potential for a wide range of applications. In this study, we synthesized Bismuth-Substituted Yttrium Iron Garnet (BiY2Fe5O12: BiYIG) using the solid-state reaction method to explore its structural, optical, and dielectric characteristics. X-ray diffraction analysis revealed the attainment of a pure cubic garnet phase in BiYIG, with a lattice parameter of 12.444 Å. Using UV–visible spectroscopy, we determined that the optical band gap of BiYIG is 2.2 eV, indicating n-type semiconductor behavior. We conducted a thorough investigation of the dielectric properties, examining capacitance, dielectric constant, dielectric loss, conductivity, impedance, and modulus, as functions of frequency and temperature. The impedance results revealed that the dielectric relaxation at room temperature was dominated by a Debye-type process, with a shift to a non-Debye-type process becoming apparent as temperature increased. Comprehensive analysis sheds light on the material's transport phenomena and optical attributes, offering insights into the potential of BiYIG for applications in magneto-dielectric and magneto-optical domains, given its high dielectric constant with low dielectric loss, and promising optical properties. These findings position BiYIG as a versatile material and underscore its suitability for advanced applications in future technological developments.

Abstract We explored the distinctive behavior of coherent and dissipative photon-magnon coupling (PMC) in dual hybrid resonators, each incorporating an Inverted Split-Ring Resonator (ISRR) paired with a Yttrium Iron Garnet (YIG) film, positioned in close proximity but with varying relative split-gap orientations. These orientations led to notable shifts in the dispersion spectra, characterized by level repulsion and attraction, signaling coherent and dissipative coupling, respectively, in single ISRR/YIG hybrids at certain orientations. Through analytical modeling, we determined that the observed shifts in coupling types are primarily due to the effect of photon-photon (ISRR-ISRR) interactions altering the phase difference between the coupled ISRR and magnon modes. Our findings highlight that precise manipulation of the relative split-gap orientations in the ISRR resonators enables controlled coherent and dissipative coupling within planar PMC systems. This capability opens new avenues for applications in quantum information technologies and quantum materials.