Novel Planer Microwave Circuit Applications and Characterization of Ni Nanowires
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1058-JJ03-06
Novel Planer Microwave Circuit Applications and Characterization of Ni Nanowires Ryan Marson1, Bijoy K Kuanr2, Sanjay R Mishra1, Robert E Camley2, and Zbigniew Celinski2 1 Physics, The University of Memphis, Manning Hall, Memphis, TN, 38152 2 Physics, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918 ABSTRACT Arrays of Ni nanorods were electrodeposited into alumina oxide templates with various lengths (11-50 µm) and fixed pore diameter (150 nm). The magnetization behavior of these rods were investigated with ferromagnetic resonance (FMR) techniques; fixed frequency (conventional FMR) and swept frequency (Network Analyzer FMR). Both resonance spectra indicate the presence of strong dipolar interaction between the nanorods. The fundamental magnetic parameters like spontaneous magnetization, gyromagnetic ratio (γ), and magnetic anisotropies of the nanorods were derived from the angular variation of resonance field H r (θ H ) data. Further, the use of nanorods as a tunable stop-band notch-filter in a coplanar waveguide geometry has been assessed. The stop-band frequency (fr) is observed to be tunable up to 24 GHz with an applied field (H) of up to 6 kOe. The theoretical fitting of f r (H ) data to resonance relation yield values of effective field (Heff) and γ, which are a little higher than the conventional FMR results.
INTRODUCTION Recently there has been a great interest in the synthesis and characterization of onedimensional materials such as nanotubes, nanobelts, nanorods, and nanowires (NW) [1-6]. A variety of materials can be obtained in the form of nanorods with diameters in the range of a few nm and lengths going up to several microns. Magneto-transport properties of low-dimensional magnetic systems have been extensively studied in the last decades because of their importance for device applications such as ultrahigh-density data storage [1-6]. In light of the increasing interest in using magnetic nanostructured materials for device applications, a complete understanding of their static and dynamic magnetic properties is required. Recently, there have been many efforts in analyzing the magnetization reversal process [4] and the magnetic microstructure of Ni and Co nanorods grown by electro-deposition. The finite length of the rods, the curling mode of magnetization, the domain-wall nucleation, and the depinning fields are some of the problems that make this analysis even more difficult. Ferromagnetic resonance [2,7,8] (FMR) is a powerful tool to characterize these magnetic systems as the resonance field (or the resonance frequency) depends directly on the key parameters of the system such as the saturation magnetization and internal anisotropies. The FMR techniques are also important because the applied field often saturates the rods and solve some of the problems mentioned above. It is also of great importance for possible device applications to quantify the distribution of the internal fields for rod arrays containing a large number of rods [6,7
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