Browsing by Author "Biswanath Bhoi"

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Control of Photon-Magnon Coupling in a Planar Hybrid Configuration
(Springer, 2024) Sachin Verma; Abhishek Maurya; Rajeev Singh; Biswanath Bhoi
Photon-magnon coupling (PMC) integrates microwave or optical photons with magnons, aiming to exploit their distinct strengths in a unified hybrid quantum system, for potential applications in quantum information science and technology. By utilizing numerical simulations, we design a planar hybrid system comprising a hexagonal-ring resonator (HRR) and yttrium iron garnet (YIG) thin film to explore the interaction between microwave photons and magnons. The anti-crossing effects between the HRR’s photon mode and the YIG’s magnon modes were observed in |S21|-frequency plots under various externally applied magnetic fields. An equivalent theoretical model, based on coupled oscillators, accurately replicated the observed anti-crossing effect and provided estimates for the PMC strength. Furthermore, we explored the behavior of the photon-magnon interaction by altering the position of the YIG film on the HRR’s track width, allowing for a more reliable control of the PMC strength variable within the range of 38.78 to 126.6 MHz (nearly 200%) in the planar-geometry HRR/YIG hybrid system. This study opens avenues for designing novel hybrid systems with effective control over the strength of PMC in a planar geometry. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Exploring doped strontium hexaferrite through micromagnetics for sub-terahertz applications
(Institute of Physics, 2025) Manjushree Maity; Rajeev Singh; Biswanath Bhoi
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 (SrFe12O19 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 (Ms) and magnetic anisotropy constant (K1). Notably, co-doping with Y3+-Al3+ and Ca2+-Al3+ 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 Ms and K1, 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. © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Fabrication, structure, and magnetic properties of pure-phase biFeO3 and MnFe2O4 nanoparticles and their nanocomposites
(Seoul National University 501-321, 2020) Inna Yusnila Khairani; Anindityo Nugra Arifiadi; Jae-Hyeok Lee; Biswanath Bhoi; Sandeep Kumar Singh Patel; Sang-Koog Kim
We fabricated pure-phase BiFeO3 (BFO) and MnFe2O4 (MFO) nanoparticles as well as their nanocomposites (BMFO), and then we studied their structures and magnetic properties. Pristine BFO nanoparticles of 93.3 nm average diameter were successfully synthesized using the sol-gel method by varying the solvent condition and the precursor amount. Pristine MFO nanoparticles with a mean diameter of 70.5 nm were synthesized using the co-precipitation method entailing the optimization of the preheating and aging steps. The fabricated MFO nanoparticles showed mostly nanospheres with few nanocubes. The nanocomposite samples of 50 % MFO and 50 % BFO were fabricated through grinding and pelletization, followed by sintering under an inert atmosphere. The crystal structures of the pristine materials in the nanocomposites were well preserved. The magnetization values (Ms) of the BFO, MFO, and BMFO were 4.9, 52, and 33 emu/g, respectively. This latter Ms value was significantly higher than that of BFO, owing to the coexistence of Fe2+ and Fe3+ in its BFO phase and the incorporation of magnetic MFO. Two synthesis methods and material properties including the structural, morphological, magnetic, and oxidation states of the BFO-MFO nanocomposites were studied in order to achieve a high Ms value of 33 emu/g, which is higher than the bulk values of previously reported BFO-MFO composite samples. © The Korean Magnetics Society.
Unveiling photon-photon coupling induced transparency and absorption
(Institute of Physics, 2024) Kuldeep Kumar Shrivastava; Ansuman Sahu; Biswanath Bhoi; Rajeev Singh
This study presents the theoretical foundations of analogous electromagnetically induced transparency and absorption, which we refer to as coupling induced transparency (CIT) and absorption (CIA), respectively, along with an exploration of the transition between these phenomena. We provide a concise phenomenological description with analytical expressions for transmission spectra and dispersion, elucidating how the interplay of coherent and dissipative interactions in a coupled system results in the emergence of level repulsion (LR) and attraction (LA), corresponding to CIT and CIA, respectively. This theory comprehensively captures both the phenomena while modelling the microstrip line loaded resonators and their couplings systematically. The model is validated through numerical simulations using a hybrid system comprising a split ring resonator (SRR) and an electric inductive-capacitive (ELC) resonator in planar geometry. We analyse two cases while keeping the ELC parameters constant, one involving a dynamic adjustment of the SRR size with a fixed split gap, and the other entailing a varying gap while maintaining a constant SRR size. Notably, in the first case, the dispersion profile of the transmission signal demonstrates LR, while the second case results in LA, effectively showcasing CIT and CIA, respectively. These simulated findings not only align with the theoretical model but also underscore the versatility of our approach. Subsequently, we extend our model to a more general case, demonstrating that a controlled transition from CIT to CIA is achievable by manipulating the dissipation rate of individual modes within the hybrid system, leading to either coherent or dissipative interactions between the modes. Our results provide a pathway for designing hybrid systems that can control the group velocity of light, offering potential applications in the fields of optical switching and quantum information technology. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.