Abstract
The frequency and temperature dependence of surface resistance of good conducting films was measured by a microwave microstrip method under various geometrical structures. The T-junction microstrip is superior to ring and strip-line resonators, which yields much accurate results with a simple fabrication process. An analysis of the transmission coefficient S21 spectra of the microstrip made of metallic aluminum films reveals that the surface resistance inherits with a one-half power law dependence on frequencies and a linear dependence on temperatures, which is in congruence with the results derived from the free electron model that only accounts on the electron-phonon interaction for a simple metal. In addition, we have specifically investigated the electron transport with strong localization effect on the DC temperature-dependent resistivity in the abnormal and normal Nb films. The results indicate a deviation from one-half power law may occur in the abnormal film. This work can be further exploited to measure the conductivity and penetration depth of metals in multilayered structure or of superconducting films. By exploiting the simplicity of a novel transport measurement on a ferromagnetic striped domain structure in a thin film of cobalt, we report the direct observation of ferromagnetic domain wall scattering. A model is proposed to describe these observations which highlights the crucial role played by electron spin precession in determining the electrical transport properties of magnetic interfaces. Conventional ferromagnetic resonance for magnetic thin films is found to be co-existed with the transmission resonance of a T-type microwave micro-strip at certain applied magnetic fields. The conductivity, the magnetization, and the magnetic anisotropic field of magnetic films can be evolved eventually from the measured resonance frequency and the quality Q factor of the resonance spectra. This work provides a closely scrutinized method to delineate the magnetic and electric properties of the deposited magnetic films succinctly. Finally, in a mimic of conventional optical reflection and transmission detection method to measure the dielectric constants of bulk materials, we develop a microwave double dielectric resonator to measure the dielectric constants of nano-metallic powders. The vacuum evaporated metallic nanoparticles are collected and filled inside the inner hole of a sapphire tube by which the resonant frequency and Q factor are measured at the TE011 mode to derive the dielectric constant.