We present results of ferromagnetic resonance (FMR) experiments and micromagnetic simulations for a distorted, 2D Kagome artificial spin ice. The distorted structure is created by continuously modulating the 2D primitive lattice translation vectors of a periodic honeycomb lattice, according to an aperiodic Fibonacci sequence used to generate 1D quasicrystals.Experimental data and micromagnetic simulations show the Fibonacci distortion causes broadening and splitting of FMR modes into multiple branches, which accompany the increasing number of segment lengths and orientations that develop with increasing distortion. When the applied field is increased in the opposite direction to the net magnetization of a segment, spin wave modes appear, disappear or suddenly shift, to signal segment magnetization reversal events. These results show the complex behavior of reversal events, as well as well-defined frequencies and frequency-field slopes of FMR modes, can be precisely tuned by varying the severity of the aperiodic lattice distortion. This type of distorted structure could therefore provide a new tool for the design of complicated magnonic systems.
We present the dynamic response of a connected Kagome artificial spin ice with emphasis on the effect of the vertex magnetization configuration on the mode characteristics. We use broadband ferromagnetic resonance (FMR) spectroscopy and micromagnetic simulations to identify and characterize resonant modes. We find the mode frequencies of elongated, single-domain film segments not only depend on the orientation of their easy-axis with respect to the applied magnetic field, but also depend on the vertex magnetization configuration, which suggests control over the FMR mode can be accomplished by altering the vertex magnetization. Moreover, we study differences between the vertex center mode (VCM) and the localized domain wall (LDW) mode. We show that the LDW mode acts as a signature of the domain wall (DW) nucleation process and the DW dynamics active during segment reversal events. The results show the VCM and LDW modes can be controlled using a field protocol, which has important implications for applications in magnonic and spintronic devices.
A halved falcate-shape dual-broadband circularly polarized printed monopole antenna is proposed. To generate the equal amplitude orthogonal modes, two halved falcate-shaped antenna are used. Also, to provide the 90 phase difference between the two modes, three stubs are used in the ground plane of the antenna. The proposed antenna provides 22.6 (1.36-1.72 GHz) and 44.4% (5.25-8.25 GHz) 3 dB axial ratio bandwidth over the lower and upper bands, respectively. By adjusting the parameters of the antenna, the lower and upper band center frequencies can be tuned individually. The proposed antenna is fabricated, and results are compared with those of the simulation. V C 2011 Wiley Periodicals, Inc.Int J RF and Microwave CAE 21:636-641, 2011.
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