Dnia 2022.06.14 (wtorek) o godzinie 14.15 w sali 2011 Wydziału Fizyki UwB, odbędzie się wykład Wydziału Fizyki na którym dr Samiran Choudhury z Max Planck Institute of Microstructure Physics, Halle, Niemcy wygłosi wykład pt.:
„Investigation and Control of Gigahertz Frequency Spin Wave Dynamics in Magnonic Crystals ”
Investigation and Control of Gigahertz Frequency Spin Wave Dynamics in Magnonic Crystals
dr Samiran Choudhury
Department of Physics Jadavpur University, Kolkata, Indie
Magnetically coupled and periodically modulated magnetic materials form a new class of artificial crystals known as magnonic crystals (MCs) where collective excitations of spin waves (magnons) can be used to carry and process information. Due to the low speed of propagation, spin waves (SWs) with frequencies in the range of high GHz have wavelengths in the nanometer regime, make MCs ideal candidates for cellular nonlinear networks and nanoscale on-chip data communications, including magnonic waveguides, SW filters, splitters, phase shifters and emitters. As a result, a new research field named magnonics has emerged which has the capability to replace current semiconductor technology. The aim of this thesis is to investigate and control the spin wave dynamics in ferromagnetic nanostructures by changing various physical and geometrical parameters such as material, shape, size, lattice spacing, lattice symmetry, and also strength and orientation of the external bias field. The static and dynamics magnetic properties of ferromagnet/nonmagnet heterostructures have been tailored by modulating external parameters such as magnetic field and electric field to develop low power consuming magnonic devices for on-chip microwave communication. The ultrafast spin dynamics have been investigated in different magnetic networks including patterned ferromagnetic structures as well as multilayered magnetic heterostructures. We have employed (1) broadband ferromagnetic resonance (FMR), (2) time-resolved magneto-optical Kerr effect (TRMOKE) magnetometer and (3) Brillouin light scattering (BLS) spectroscopy to probe the frequency-, time- and wavevector-resolved magnetization dynamics, respectively. The modulation of magnetic properties has been explored in three distinct genres of magnetic systems during this work:
I. 2D Magnetic Antidot Systems: We have investigated the effects of geometrical parameters and the applied magnetic field orientation on the spin wave properties in a two-dimensional array of Ni80Fe20 antidots in the form of 2D magnonic crystals.
II. 2D Bicomponent Magnetic Nanostructures: We have probed the modification of the spin dynamics in 2D bicomponent magnonic crystals (BMCs) where one ferromagnetic element is embedded periodically in another magnetic matrix with contrasting magnetic parameters (e.g. saturation magnetization). As a result, the coupling is enhanced between these two materials through their lateral interfaces. The effects of geometrical parameters and the applied magnetic field orientation on the magnetization properties have been investigated.
III. Magnetic Heterostructures with Ultrathin Ferromagnetic Layers: We have further studied the dynamic magnetic properties in CoFeB/MgO heterostructures using magneto-electric effect by controlling perpendicular magnetic anisotropy present at CoFeB/MgO interfaces
under the application of electric field (voltage). We have further investigated the reconfigurable magnonic band structure and band gap in a dynamic 1D magnonic crystal composed of CoFeB/MgO heterostructure under the influence of electric field. This can unlock a gateway to develop a new genre of MCs invoked by an energy-efficient stimulus,
i.e. electric field which may play a key role in devicing spin-based magnonic circuits with ultralow power consuption.