Magnetoelastic and magnetostatic wave propagation in non-ellipsoidal ferrimagnets
Başlık:
Magnetoelastic and magnetostatic wave propagation in non-ellipsoidal ferrimagnets
Yazar:
Yazgan, Bingul, author.
ISBN:
9780438054561
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (344 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: J. H. Collins.
Özet:
Magnetoelastic and magnetostatic wave propagation properties are investigated in nonellipsoidal ferrimagnetic structures. The thesis is divided into nine chapters. Chapter 1, the introduction, is a summary of spin and magnetoelastic mode characteristics in an infinite medium. General equations, the equation of motion and Hamiltonian of the ferrimagnetic medium, and the dispersion relations of various modes are introduced. In Chapter 2, mode generation using nonuniform internal magnetostatic fields of nonellipsoidal samples is discussed. The spin wave mode equation and its solutions for one dimensional internal field variation, conversion efficiencies from electro-magnetic to spin waves, magnetoelastic interaction and coupled mode propagation in a slowly varying internal field, magnetostatic modes of the disc and rod geometries, calculation of demagnetization fields, and delay times of various propagating modes are explained. Chapter 3 describes the experimental results (delay, insertion loss, C4 absorbtion characteristics for various YIG rod and disc geometries, at X and S band frequencies excited in microwave resonant cavities at room temperature, and compares these results with the theory. In Chapter 4, 'composite structures' namely identical diameter single crystal YIG and polycrystalline ferrite discs and short rods which are joined together to shape the internal field in the single crystal for-different delay characteristics are discussed. S band results are given, showing magnetoelastic mode excitation at various directions with respect to the DC field. Chapter 5 concerns polycrystalline sleeve loaded rod delay characteristics (branch phenomenon in the delayfield graphs, constant delay in a large field variation), internal field and delay calculations, discussion of concave and convex type internal fields, detectable propagation regions in the structure, significance of the inflection points of the axial demagnetizing field. A large number of experimental results covering each possible case are presented. The practicability of two port propagation is discussed. In Chapter 6 a theoretical study is given which applies ray theory of geometrical optics to spin waves and magnetoelastic waves, lens action of the two dimensional internal field, and diffraction properties of various geometries, wave vector and energy velocity directions in the inhomogeneous and anisotropic medium are investigated. The theory is compared with the experimental results. Chapter 7 outlines the high power effects (nonlinearities) in the magnetoelastic regime. For the rod geometry, CW and pulse results are presented at high powers. Low frequency oscillations appearing at the cavity output signal are investigated. In Chapter 8 measurement techniques used at S and X band frequencies are summarized, cavity details are given. The last chapter reviews the important characteristics of the delay medium found during the course of the study and points out the possibilities to improve them. (Abstract shortened by ProQuest.).
Notlar:
School code: 0547
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684502.1) | 684502-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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