International Journal of

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We study the focusing properties of a two dimensional complex square-lattice photonic crystal (PC) comprising air holes immersed in Ge medium. The finite difference time domain (FDTD) method is utilized to calculate the dispersion band diagram and to simulate the image formation incorporating the perfectly matched layer (PML) boundary condition. In contrast to the common square PCs with the same air filling factor, the frequency corresponding to the effective negative refraction occurs in the second photonic band and the spatial image resolution is improved.

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In this study, copper cobalt ferrite nanoparticles were synthesized by chemical formula Co_1-xCu_xFe₂O₄ and (x=0, 0.2, 0.4, 0.6, 0.8, 1) by co-precipitation method. The X-ray diffraction pattern of the samples confirmed the single-phase spinel structure of the fabricated nanoparticles and the average size of the crystals was calculated from the entire width of the diffraction peak with the highest intensity and Scherrer relationship. Using transmission electron microscope images, the nanoparticle size was about 10 nm. The magnetic properties of copper cobalt ferrite nanoparticles were measured by AGFM and it was seen that with increasing substitution of copper Cations instead of cobalt Cations in the samples, the amount of induction decreased and the saturation magnetization first increased and then decreased. In order to investigate the Faraday effect on copper cobalt ferrite nanoparticles, the transmittance values were measured using a laboratory experiment and their graphs were plotted in terms of the applied magnetic field, all of which were in agreement with the theory. In addition, transmittance was investigated for two angular positions of the analyzer at -45˚ and +45˚ in different fields.