Sharif Digital Repository

We present experimental data for artificial metaconductors exhibiting skin effect suppression at microwave frequencies. The metaconductor consists of a stack comprising twelve periods of alternating ferromagnetic (Permalloy) and normal metal (Cu) layers. Near the effective antiferromagnetic resonant frequency the average in-plane magnetic permeability of the stack approaches zero, leading to an increase in the skin depth. Compared to a Cu-based device, up to 70% loss reduction has been achieved by a metaconductor based coplanar wave guide at ∼ 10 GHz without changing the propagation wavelength. Moreover, unlike conventional magnetic devices, no external magnetic bias is required due to the... 

We demonstrate high-quality integrated inductors built from a multilayer of alternating copper and ferromagnetic films. The multilayer acts as a meta-conductor whose effective permeability becomes nearly zero at its ferromagnetic anti-resonance frequency. This leads to a suppression of the skin effect and a significant increase in the quality factor of the device. Experiments show an up to 86% increase in quality factor compared to conventional copper-based spiral inductors at high frequencies  

The electronic conductor-insulator transition in Ca-doped BiFeO 3 films grown by pulsed-laser deposition technique has been investigated. Nature of the transition is resolved to be Mott type through the control of band-filling. Calcium resolved to have colossal effect on enhancing the electrical conductivity of BiFeO 3, but it did not affect band gap of the mother phase perceptibly. UV-visible study yielded band gap of 2.72-2.81 eV (at 300 K) for different concentrations of calcium. Both UV-visible and photoluminescence spectra revealed sub-band gap transitions at 2.17 and 2.38 eV, of which the latter might be ascribed to the oxygen vacancies  

A thin film microextraction method using elecrospun magnetic polybutylene terephthalate nanofibers is developed and implemented to isolate some selected triazines. Due to the high mechanical stability of these nanofibers, they are repeatedly used under harsh magnetic stirring and ultrasonic conditions without any damage and structure degradation. The presence of magnetic nanoparticles within the nanofiber structure increases the extraction efficiency while the fibers could be collected by an external magnet. The synthesized nanocomposite showed strong affinity toward the selected analytes. Apart from the concentration of magnetic nanoparticles within the nanocomposite network, the effect of...