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  • 1
    Electronic Resource
    Electronic Resource
    Methods for determination of microwave cavity quality factors from equivalent electronic circuit models (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 439-443 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Simple analytic methods have been developed for high-accuracy measurement of the quality factor Q of reflection and transmission microwave cavities. These methods are based on the consideration of cavity equivalent electronic circuit models and use measured cavity parameters over a narrow frequency range spanning the cavity resonance frequency to determine the Q factor. Since only straightforward frequency and power measurements are necessary, these methods are well suited to computer-aided data acquisition and analysis. Specific results are presented for a standard X-band reflection cavity with a Q of 2699.1±0.5 and a high-Q X-band cylindrical cavity with a Q of 23112±4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140397
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  • 2
    Electronic Resource
    Electronic Resource
    Domain Wall Motion in Double Nickel–Iron Films (1967)
    [s.l.] : Nature Publishing Group
    Nature 213 (1967), S. 1010-1011 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] For both techniques, single isolated domain walls are moved across the film using a number of short easy-axis field pulses of known duration and amplitude. Middel-hoek's technique uses a large number (about 500) of very short pulses (20-800 nsec). The technique used by Patton and Humphrey2'4, on ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2131010a0
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetostatic wave dynamic magnetization response in yttrium iron garnet films (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1595-1603 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamic microwave magnetization (DMM) amplitude of magnetostatic waves in yttrium iron garnet films at 5–6 GHz has been measured as a function of input power. The measurement is based on the characteristic frequency shift in the power transmission spectrum. This shift is related to the reduction of the effective static magnetization and, therefore, the increase of the DMM amplitude at high power. The measurements were made on 7.2-μm-thick, single-crystal yttrium iron garnet films. A pulsed frequency-swept microwave signal at 5–6 GHz was used to launch the magnetostatic waves. The signals were excited and detected by planar microstrip transducers. Measurements were made for magnetostatic forward volume waves (MSFVW) and magnetostatic surface waves (MSSW). The duty cycle of the pulsed microwave signal was kept at 0.1% in order to avoid sample heating effects. The shifts for small features in the transmission vs frequency profiles were used to determine the DMM amplitudes. At low power, the DMM amplitude increased with power. Saturation occurred at high power. The results indicate a saturation DMM response at about 10% of the saturation magnetization for input power in the 3–4 W range for MSFVW signals and above 0.5 W for MSSW signals. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361003
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  • 4
    Electronic Resource
    Electronic Resource
    High-field effective linewidth and eddy current losses in moderate conductivity single-crystal M-type barium hexagonal ferrite disks at 10–60 GHz (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2705-2718 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The losses associated with the high-field tail region of the ferromagnetic resonance (FMR) absorption curve were investigated at 10, 19, 35, and 60 GHz for 0.10–1.75-mm-thick c-plane circular disks of flux-grown single-crystal M-type barium ferrite materials. A conventional high-field effective linewidth analysis of the data yielded an effective linewidth which increased with the square of the disk thickness and linearly with frequency, dependencies which indicate a predominant eddy current loss process. Based on these results, an eddy current loss analysis of the tail region was done, based on the insulator FMR response and eddy current losses driven by the FMR response. This analysis leads to a new noninvasive technique for the determination of the microwave conductivity in moderate conductivity ferrites. One obtains the conductivity from an appropriate analysis of the FMR absorption tail in the same way that analysis of the magnetic loss tail yields a high-field effective linewidth. Based on this technique, the microwave conductivity of these flux-grown barium ferrite single-crystal materials was determined as a function of frequency and found to increase linearly from 0.033±0.004 Ω−1 cm−1 at 10 GHz to 0.10±0.02 Ω−1 cm−1 at 60 GHz. These results are consistent with a measured dc conductivity of 0.03–0.05 Ω−1 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354665
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  • 5
    Electronic Resource
    Electronic Resource
    Backward volume wave solitons in a yttrium iron garnet film (invited) (abstract) : Proceedings of the 37th annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2146-2147 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solitons are nonlinear propagating wave pulses that preserve their shape without spreading. Recently, microwave envelope solitons have been observed in thin yttrium iron garnet (YIG) films for magnetostatic surface wave and forward volume wave configurations. In this work, we report the first observation of microwave envelope of magnetostatic backward volume waves (MSBVW) for an in-plane magnetized YIG film with waves propagating parallel to the magnetization direction. Both soliton profiles and the nonlinear peak power response were observed. The experiments were conducted using a microstrip magnetostatic wave delay line structure. A single crystal YIG film of 7.2 μm thickness, 2 mm×15 mm in size, and with unpinned surface spins was magnetized in-plane by a static external field of 1343 Oe along the long 15 mm edge. The 10 GHz ferromagnetic resonance linewidth of the film was 0.6 Oe. Square microwave pulses with pulse widths from 2 to 200 ns and a carrier frequency of 5.78 GHz were launched parallel to the field through a microstrip antenna. The output signal was received by a second microstrip antenna placed 4 mm downstream and analyzed in the time domain with a microwave transition analyzer. Envelope soliton behavior evident from the time resolved waveforms was observed for various input-power/pulse-width combinations.At relatively low power levels, one sees a broad output signal with a peak power increasing linearly with the input power. As the input power is increased above some threshold, a sharp soliton pulse emerges and the peak power increases more rapidly with input power than in the low power regime. The threshold varies with pulse width, as expected for solitons. A further increase of the input power produces multiple soliton profiles and a corresponding drop in the peak power. These results clearly demonstrate the existence of MSBVW solitons in YIG films. Dr. J. D. Adam of Westinghouse is acknowledged for providing the YIG films. This work was supported in part by the National Science Foundation, Grant No. DMR-8921761 and by the U. S. Army Research Office, Grant No. DAAL03-91-G-0327.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354745
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  • 6
    Electronic Resource
    Electronic Resource
    Propagation properties of microwave magnetic envelope solitons in thin yttrium–iron–garnet films at 5 GHz (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4879-4879 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microwave magnetic wave packets propagating in thin yttrium–iron–garnet (YIG) films show potential for novel devices as well as improved understanding of the basic properties of linear and nonlinear waves. The propagation characteristics of these excitations that have been studied up to now, however, do not provide a clear separation between linear and soliton regimes or a clear separation of the different contributions to the decay during propagation. The objective of this work was to study such characteristics for 5 GHz, 13–40 ns wide backward volume wave (BVW) magnetostatic wave square pulses in both the low-power linear and in the high-power soliton regimes and address these issues. The measurements were made with a delay time structure with a long and narrow 7.2 μm thick YIG film and 50 μm wide transducers, and input powers from 5 mW to 2 W. The output peak power Pout versus input pulse power Pin exhibits the same nonlinear response reported previously,1 with a linear response region A followed by a region B response with a more rapid increase in Pout and a high power region C in which Pout goes through a maximum and decreases. However, the integrated output pulse power, or pulse energy, is a strictly linear function of input pulse power over both the A and the B regions. At the same time, one finds a small but measurable increase in the average propagation velocity for the pulses as power is increased. The measured decay in the total pulse energy with propagation time leads to an unambiguous separation of the decay contributions due to dispersion and loss. This allows, in turn, a clear separation between the linear pulse and soliton regimes. The results were modeled from the nonlinear Schrödinger (NLS) equation with propagation and damping terms included. Agreement is good for regions A and B but the NLS model fails completely for region C.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364865
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  • 7
    Electronic Resource
    Electronic Resource
    High field effective linewidth and eddy current losses in moderate conductivity single crystal Zn-Y hexagonal ferrite at 10–35 GHz (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 432-442 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microwave losses associated with the extreme high field tail region of the ferromagnetic resonance (FMR) absorption curve for 0.08- to 1.38-mm-thick c-plane circular disks of single crystal Zn-Y hexagonal ferrite materials with planar anisotropy were investigated at 10, 19.3, and 35.3 GHz, with the static external magnetic field applied in plane. Analysis of the data in terms of magnetic losses only gave anomalous high field effective linewidth ΔHF results; this ΔHF showed a substantial increase with the field, changed with both disk thickness and radius, and was higher for an out-of-plane microwave field direction than for an in-plane direction. This linewidth did scale with the square of the disk thickness, one indication of predominant eddy current losses. The data were then analyzed in terms of eddy current losses, based on the assumption of an insulator FMR response and a high field eddy current loss absorption tail driven by that response. The predictions of the model were in good agreement with the data. Fits to the data gave reasonable and consistent values of the microwave conductivity which ranged from 0.03 to 0.05 Ω−1 cm−1 at 10 GHz to 0.06–0.07 Ω−1 cm−1 at 35 GHz, relative to a measured dc conductivity of 0.02–0.03 Ω−1 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357093
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  • 8
    Electronic Resource
    Electronic Resource
    A numerical study of nonlinear Schrödinger equation solutions for microwave solitons in magnetic thin films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3906-3909 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dipole-exchange spin wave pulses in magnetic thin films have been numerically modeled with the nonlinear Schrödinger equation. Small input pulse amplitudes yield propagating wave packets which exhibit a linear response. As the amplitude of the input pulse is increased, the propagating spin-wave pulse exhibits soliton and then multisoliton structures. In the soliton regime, three principal characteristics are observed. First, in the zero damping limit, the soliton propagates without changing its shape. Second, the soliton exhibits an inherent velocity in addition to its linear group velocity. Third, the soliton exhibits a damping rate that is approximately twice that in the linear regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352878
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  • 9
    Electronic Resource
    Electronic Resource
    Forward volume wave microwave envelope solitons in yttrium iron garnet films: Propagation, decay, and collision (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4274-4289 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetostatic forward volume wave (FVW) microwave magnetic envelope solitons in 7.2 μm thick, single-crystal yttrium iron garnet films have been studied at 5.6–6.0 GHz. Rectangular input pulses with peak powers up to 3 W and pulse widths 5–50 ns were used. Single soliton output pulses with a characteristic increase in amplitude and pulse narrowing are observed when the power or width of the rectangular input microwave pulse exceeds threshold levels. Above these levels, output pulse peak power versus input power or pulse width exhibits a nonlinear increase and shows saturation effects. Multiple peak output profiles are observed for pulse powers and widths well above threshold. Solitons could be formed for all frequencies within the usable, low transmission loss portion of the magnetostatic FVW band. The use of reflected pulses from the film edge made it possible to study soliton decay and soliton collisions. The soliton decay rate was found to be approximately twice the linear rate, as expected from theory. The collision of solitons was found to occur with no significant change in shape and velocity. The various characteristic times from theory for pulse decay, pulse dispersion, nonlinear response, and propagation are found to be consistent with the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357312
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  • 10
    Electronic Resource
    Electronic Resource
    New perspective on the Green's function dipole-exchange spin wave theory for thin films (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6084-6084 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In contrast with the scalar potential theory for dipole-exchange spin waves in thin films, the Green's function (GF) approach in combination with perturbation methods (PM) gives simple closed form dispersion equations, analytical expressions for the dipole-exchange frequency gaps, and good intuitive physics. However, in the case of in-plane magnetized films and perpendicular propagation, the GF/PM results present two major problems. (1) The multibranch dipole-exchange solutions bear little resemblance to the single dispersion curve for the well-established Damon–Eshbach magnetostatic surface modes and the nonreciprocal mode profiles predicted by the simple theory and observed experimentally. (2) The lowest order exchange branch has a curvature that is much greater than expected from either simple spin wave considerations or scalar potential theory. To resolve these problems, a simple method has been developed to solve the coupled mode equations obtained from the GF formalism without recourse to perturbation methods. The coupled mode dispersion relations obtained with this method are valid for an arbitrary field configuration and propagation direction, and are not subject to the restrictions imposed by perturbation methods. The solutions agree well with the surface mode theory for in-plane magnetized films. Good agreement is also found with the Brillouin light scattering data for iron thin films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355465
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