Research
Current Research during Ph.D.
Research Area: "Photon-Magnon Coupled Hybrid System for quantum information processing and spintronic technologies".
"To investigate the emergent properties due to light-matter interaction for Next-Generation Information Processing Technology".
1. Control of Photon-Magnon Coupling in a Planar Hybrid System
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 hexagonal-ring resonator (HRR)'s photon mode and the yttrium iron garnet (YIG)'s magnon modes were observed in |S21|-frequency plots under various externally applied magnetic fields.
Fig. 1. Schematic illustrations of the sample structure and simulation setup geometry. (a) The sample consists of a YIG film (green), a microstrip line (dark yellow), a dielectric material (gray), and a single HRR positioned near the microstrip line. A uniform external static magnetic field (H) is applied along the y-direction to bias the YIG thin film. (b) The schematic figure depicts the six different positions of YIG film on HRR edges, denoted by distinct angles (φ) ranging from 0º to 360º in a clockwise rotation with a 60º difference with respect to the microstrip line.
Fig. 2. |S21| transmission spectra shown in Fig. 3 represented by the |S21| power on the plane of microwave frequency and magnetic field plane (f-H plane) (a) only for the HRR, (b) for YIG film only and (c) for the planer hybrid system of HRR and YIG thin film.
2. Studies of magnetic and microwave properties of sputter deposited polycrystalline YIG thin films
Yttrium iron garnet (YIG) is an ideal magnetic material with potential applications in microwave and spintronic devices. A key prerequisite for seamless integration into current semiconductor electronics is the growth of high-quality YIG films on substrates beyond isostructural Gadolinium gallium garnet. In this context, we present the successful fabrication of YIG thin films with varying thicknesses (70 ≤ t ≤ 380) on fused quartz substrates utilizing radio-frequency (rf) magnetron sputtering. The Rietveld refinement of the X-ray diffraction data uncovers the formation of body-centered cubic single-phase polycrystalline YIG with the space group of Ia-3d. The saturation magnetization (4πM) and coercivity (HC), as determined by the physical property measurement system (PPMS), exhibit a dependence on the film’s thickness (t). Remarkably, the film with t = 380 nm shows a 4πM value of 1775, closely resembling the bulk YIG value, with an exceptionally low coercivity (HC < 5 Oe). From ferromagnetic resonance (FMR) measurements, the estimated effective saturation magnetization (4πMef) is found to be very much different from the 4πM obtained from PPMS and is attributed to the presence of stressed-induced magnetic anisotropy (HK) in YIG films. The FMR linewidth (ΔH) of the YIG films is found to be quite sensitive to HK and the minimum ΔH value of 80 Oe is observed in the film with the lowest HK. The findings indicate that YIG films deposited on quartz substrates have potential advantages for their application in semiconductor-integrated devices.
Fig. 1. Rietveld-refined XRD patterns of YIG thin films of different thicknesses. The black circles and the red solid line are the experimental and calculated XRD patterns respectively.
Fig. 2. Three-dimensional AFM image for 70 nm, 250 nm, 345 nm and 380 nm thick YIG flm
Fig. 3. a Room-temperature M–H loop of YIG thin flms of varying thickness. Inset: variation of coercivity (HC) as a function of grain size.
Fig. 4. Parallel (red line) and perpendicular (blue line) FMR spectra of YIG thin films of different thicknesses measured at room temperature
Previous Research (During M.Sc.)
M.Sc. Project: "Phase Ordering Kinetics in fluids: A Langevin Dynamics Study"
The main objective of this M.Sc. project was to obtain a better understanding of the molecular dynamics for L-J potential though the computation of the Potential Energy, Kinetic Energy, Total Energy, Radial Distribution Function (RDF) and Temperature for different systems in different ensembles.
In this project, has been computed first the MD simulation for the microcanonical ensemble. It has been found that the microcanonical studied by molecular dynamics simulations in 3D systems were systems of a few thousand of atoms. Therefore, it has been reached that there is fluctuations in potential energy and in kinetic energy but total energy is constant with respect to time, there is no fluctuations in total energy. And then computed the MD simulation for the canonical ensemble using the Anderson method. It has been found that the canonical ensemble studied by molecular dynamics simulations in 3D systems were systems of a few thousand of atoms. Therefore, it has been reached that there is fluctuations in potential energy and in total energy but kinetic energy is constant with respect to time, there is no fluctuations in kinetic energy.