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Precessional Magnetization Dynamics and Spin Waves in 3D Ferromagnetic Nanostructures
Published in Gianluca Gubbiotti, Three-Dimensional Magnonics, 2019
Sucheta Mondal, Sourav Sahoo, Anjan Barman
where W is the energy function for restoring force, G is the gyrovector for gyroforce, and Xj is the position of the jth core. If external perturbation is applied to the core in the presence of another bias magnetic field, the frequency of excitations scales with the field value. It is also found that the vortex state can still exist without having an out-of-plane core if the “singularity” can be physically removed. Inside an exchange-biased elliptical nanoring in the absence of any core, the chirality (CW or CCW) of the vortex varies as a function of the external magnetic field and exchange bias angle [116]. The core of the vortex can be reversed by an application of a short burst of magnetic field [117], from current- driven resonant dynamics of the vortex [118], spin current [119], or spin-polarized current [120]. The switching of the vortex core can be useful for efficient data writing in a storage device having data stored inside a nanometric core.
Lifetime properties of graphene square-nanoring gratings based on tunable surface plasmon
Published in Journal of Modern Optics, 2019
Yichen Zhang, Jie Zhan, Lingxi Wu, Suxia Xie, Qiong Liu, Zhaohui Chen
To conclude, we numerically analyse a tunable surface plasmon nanoscale structure consists of graphene square rings in mid-infrared range. There was a good agreement between the finite difference time domain (FDTD) simulations and the coupled mode theory (CMT) theoretical results, which indicates that the resonant modes and intensity of optical absorption can be tuned by adjust of Fermi energy of graphene or carrier mobility in the graphene square-nanoring. In addition, by analysing the simulated absorption spectra for the different inner lengths of graphene square-nanoring gratings and the different refractive index of substrate material, we find that the change of inner length and the refractive index will affect the resonant wavelength and absorption. Modulating the resonant frequencies and enhancing optical absorption is the key links of designing plasmonic devices in the future. As applications, our proposed structure and results show a great promise on the realization of graphene plasmonic optical-devices can be used to construct solar cells, sensors and modulators in the mid-infrared range.
A novel plasmonic elliptical nanocluster and investigating Fano response in π- and T-shaped arrays
Published in Electromagnetics, 2018
Maryam Bazgir, Shohreh Nouri Novin, Ferdows B. Zarrabi, Samaneh Heydari, Afsaneh Saee Arezoomand
In plasmonic nanostructures, Fano resonances arise from the near-fields coupling between the bright (radiating) modes and the dark (none radiating) modes (Gallinet and Martin 2011). The plasmonic structures have been exhibiting Fano resonances with various formations such as ring disk nanocavities (Cetin and Altug 2012), nanodisk with symmetry breaking (Hao et al. 2008), nanoshell (Peña-Rodríguez et al. 2013), NPs coupling with substrate (Mock et al. 2008), plasmonic heptamers clusters comprising split nanoring (Liu, et al. 2012), E-shape gold plasmonic nanocavity (Sun et al. 2014), plasmonic oligomer clusters like octamer, nanomer, decamer, and undecamer (Ye et al. 2012).
Tunable plasmon-induced transparency based on graphene nanoring coupling with graphene nanostrips
Published in Journal of Modern Optics, 2018
Chang-Long Liao, Guang-Lai Fu, Sheng-Xuan Xia, Hong-Ju Li, Xiang Zhai, Ling-Ling Wang
In summary, we design a planar graphene nanostructure that consists of a nanoring resonator and paired nanostrips to realize a PIT spectral response at the mid-infrared region. The coupling between the nanoring and paired nanostrips gives rise to a transparency window in the transmission spectrum, which results in very large group delays at the transparency window. The shift of the resonance wavelength per RIU can reach to 4833 nm/RIU. Importantly, the PIT spectrum can be tuned by adjusting the geometric parameters as well as the Fermi level of graphene. The proposed graphene nanostructure could be a good platform for slow light, optical sensing and switching applications.