Browsing by Subject "nanowire"
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Item Spin Relaxation and Size Effects in Cu and Al Nanowires(2018-12) Watts, JustinThis dissertation focuses on the quantification of dominant spin relaxation sources in Cu and Al. In light metals, the Elliott-Yafet (EY) theory is widely acknowledged to describe the proportionality between the spin relaxation rate and the momentum scattering rate for a single scattering source. However, the quantitative impact on spin relaxation due to the presence of multiple scattering sources has remained poorly understood. By integrating Cu and Al nanowires into non-local spin valves (NLSVs), spin and charge transport were separately characterized. We test a proposed generalization of the EY theory, where each scattering source is assigned a unique EY proportionality constant. Verification of the generalized EY theory and quantification of the EY constants for specific scattering sources (e.g., phonons, surfaces, grain boundaries, non-magnetic impurities, and local moments), then enables predictive spin relaxation models and improves understanding of specific spin relaxation sources in these model metals.Item Study of Nanowires for Microwave and Millimeter Wave Frequency Applications(2021-12) Zhang, YaliThis dissertation discusses the application of nanowire (NW) technology applied in millimeter wave and sub-millimeter wave frequency bands. Both magnetic nanowires (MNWs) and copper (Cu) NWs are studied. MNW is proposed for use as bio-labels in nanomedicine application and as magnetic substrate in non-reciprocal design for communication application. To do that, the ferromagnetic resonance (FMR) technique is adopted for MNWs characterization. Cu NW is investigated for use as vertical interconnect in integrated circuit (IC) for wireless communication applications. A coplanar waveguide (CPW) with NW Cu vias design was proposed and studied.The theory and simulation model of MNWs and Cu NWs are first discussed to provide preliminary understanding of the FMR of MNWs and concepts of Cu NW-based vias (chapter 2). Then the MNWs are fully characterized in the DC field domain. The FMR characterization system and methods are developed. The factors that influence the FMR characterization are studied. A tri-labeling system is built based on nickel (Ni), cobalt (Co) and iron (Fe) MNWs. The MNWs in a bio-mimicking and biological media are characterized (chapter 3). Next, to use MNWs in non-reciprocal devices, three key parameters are defined, FMR frequencies, permeability, and linewidth. A complete characterization method is developed to acquire these three parameters accurately (chapter 4). Lastly, the Cu NWs vias in a CPW structure are designed, fabricated, and measured in three frequency bands 0.04-40 GHz, 0.01- 67 GHz and 0.01-110 GHz. The NW via loss is extracted and compared to other advanced via technologies. A comparison of NW and conventional via is also presented. (chapter 5). The outcome of different study investigated in this work show the promising potential of NWs as a favorable material for future biomedical and communication applications.