Anisotropy of magnetostatic wave group velocities in ferromagnetic waveguides

2016 ◽  
Author(s):  
Гришин ◽  
S. Grishin ◽  
Садовников ◽  
A. Sadovnikov ◽  
Романенко ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetostatic Wave ◽  
Bias Magnetic Field ◽  
External Bias ◽  
Micron Size ◽  
Magnetostatic Waves ◽  
Phase And Group Velocities ◽  
Axis Of Symmetry ◽  
The Difference ◽  
Group Velocities

The results of theoretical and experimental study of anisotropic propagation of magnetostatic waves (MSW) in ferromagnetic thin-film microsize waveguides are presented. Electrodynamic model of tangentially magnetized ferromagnetic waveguide is developed. On the base of the model, the main features in rotation of group velocity vector of volume MSW (VMSW) by rotating a wave vector and a vector of an external bias magnetic field relative to the axis of symmetry of the waveguide are demonstrated. It is shown, that a decrease in a width of the waveguide to the micron size leads to non-reciprocal propagation of VMSW and to increase of angular divergence between the phase and group velocities of VMSW. The experimental research of T-shaped ferromagnetic microwaveguide demonstrates the difference in power levels of a signal that is branched in the shoulders of T-shaped waveguide when the bias magnetic field is rotated in the waveguide plane.

Magneto-Static Wave Oscillator-Based Integrated Magneto-Optic Bragg Cell Modulator*

1998 ◽  
Vol 517 ◽  
Author(s):  
Jun Su ◽  
Chen S. Tsai
Keyword(s):  
Magnetic Field ◽  
Carrier Frequency ◽  
Delay Line ◽  
Magnetostatic Wave ◽  
Bias Magnetic Field ◽  
Volume Wave ◽  
External Bias ◽  
Wave Oscillator ◽  
Oscillator Type ◽  
Insertion Losses

AbstractA novel magnetooptic (MO) Bragg cell modulator that utilizes a magnetostatic forward volume wave (MSFVW) oscillator is presented. The carrier frequency of the MSFVW signals involved in the MO interaction is tuned linearly from 2.112 to 3.274 GHz by increasing an external bias magnetic field from 2350 to 2900 Oe. Compared with a conventional magnetostatic wave (MSW) delay line-based MO Bragg cell modulator, the proposed modulator can provide significantly higher diffraction efficiency owing to reduction of insertion losses in the MSFVW oscillator. Furthermore, the oscillator-type MO modulator can be more easily integrated with other MMIC devices.

The dispersion of surface waves on multilayered media*

1953 ◽  
Vol 43 (1) ◽  
pp. 17-34 ◽  
Author(s):  
N. A. Haskell
Keyword(s):  
Surface Waves ◽  
Rayleigh Waves ◽  
Matrix Formalism ◽  
Multilayered Media ◽  
Solid Media ◽  
Phase Velocity Dispersion ◽  
Phase And Group Velocities ◽  
Horizontal Heterogeneity ◽  
The Difference ◽  
Group Velocities

abstract A matrix formalism developed by W. T. Thomson is used to obtain the phase velocity dispersion equations for elastic surface waves of Rayleigh and Love type on multilayered solid media. The method is used to compute phase and group velocities of Rayleigh waves for two assumed three-layer models and one two-layer model of the earth's crust in the continents. The computed group velocity curves are compared with published values of the group velocities at various frequencies of Rayleigh waves over continental paths. The scatter of the observed values is larger than the difference between the three computed curves. It is believed that not all of this scatter is due to observational errors, but probably represents a real horizontal heterogeneity of the continental crusts.

scholarly journals Two Kinds of Vacuum in Casimir Effect

2021 ◽  
pp. 61-77
Author(s):  
Huang Zhi-Xun
Keyword(s):  
Electromagnetic Waves ◽  
Casimir Effect ◽  
Refraction Index ◽  
Physical Reality ◽  
Negative Energy ◽  
Physical Vacuum ◽  
Quantum Vacuum ◽  
Phase And Group Velocities ◽  
The Difference ◽  
Group Velocities

The Casimir effect is one observable of the existence of the vacuum energy, i.e. the existence of vacuum electromagnetic field. The meaning of this word "vacuum" is physical vacuum, not technology vacuum. Then, we say that the change in the vacuum structure enforced by the plates. There are two kinds of vacuum, one is usual vacua or free vacua (outside the plates). Another is the negative energy vacua (inside the plates), and the refraction index less than 1(n<1). That cause a change in the light speed for electromagnetic waves propagating perpendicular to the plates: △c/c1.6×10-60d-4, and d is the plate distance. When d=10-9m(1nm), △c=10-24c. Then, a two-loop QED effect cause the phase and group velocities of an electromagnetic wave to slightly exceed c. Though the difference are very small, that raise interesting matters of principle. The focus of this paper is to improve the understanding of the nature of quantum vacuum. In the past, to say that "vacuum is not empty" was already a criticism and subversion of classical physics. Now it seems doubly strange to say that there is a negative energy vacuum that is "empty"than the normal physical vacuum. But these theories are rigorously justified; Casimir effect can create an environment with refractive index less than 1(n<1) and lead to the appearance of superluminality, which is one of the representations of "quantum superluminality". These advances in basic science will certainly open up new fields of application, In short, it is not the Casimir structure that creates the quantum vacuum, but the structure that makes the quantum vacuum "emerge"in a clever way as a perceptible physical reality. This is truly a scientific achievement.

scholarly journals Поверхностные магнитостатические волны в пленках железо-иттриевого граната с поверхностной субволновой метаструктурой из пленки пермаллоя

2020 ◽  
Vol 62 (9) ◽  
pp. 1494
Author(s):  
С.Л. Высоцкий ◽  
Ю.В. Хивинцев ◽  
В.К. Сахаров ◽  
Н.Н. Новицкий ◽  
Г.М. Дудко ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Transmission Coefficient ◽  
Yttrium Iron Garnet ◽  
Permalloy Film ◽  
Frequency Range ◽  
Yttrium Iron ◽  
Magnetostatic Waves ◽  
Axis Of Symmetry ◽  
Iron Garnet

The frequency dependencies of the transmission coefficient of surface magnetostatic waves (SMSW) propagating in subwavelength magnonic structures obtained by depositing of 1D and 2D thin-film metastructures based on a permalloy film 40 nm thick onto the surface of yttrium iron garnet (YIG) film were experimentally studied. Such structures in the frequency range 1–10 GHz (typical for the study of SMSW in YIG films) lead to modulation of attenuation and the effective internal magnetic field in the YIG film. The possibility of controlling the parameters of the bandwidth of the SMSW by the choice of the direction of magnetization in the plane of the structures relative to their axis of symmetry is shown.

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

Asymptotic derivation of a refined equation for an elastic beam resting on a Winkler foundation

2021 ◽  
pp. 108128652110238
Author(s):  
Barış Erbaş ◽  
Julius Kaplunov ◽  
Isaac Elishakoff
Keyword(s):  
Ad Hoc ◽  
Moving Load ◽  
Low Frequency ◽  
Elastic Beam ◽  
Winkler Foundation ◽  
One Dimensional ◽  
Beam Equations ◽  
Dimensional Equation ◽  
Phase And Group Velocities ◽  
Group Velocities

A two-dimensional mixed problem for a thin elastic strip resting on a Winkler foundation is considered within the framework of plane stress setup. The relative stiffness of the foundation is supposed to be small to ensure low-frequency vibrations. Asymptotic analysis at a higher order results in a one-dimensional equation of bending motion refining numerous ad hoc developments starting from Timoshenko-type beam equations. Two-term expansions through the foundation stiffness are presented for phase and group velocities, as well as for the critical velocity of a moving load. In addition, the formula for the longitudinal displacements of the beam due to its transverse compression is derived.

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