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Analysis of an Electromagnetic Wave on the Boundary between Electromagnetic Materials
Kadlec, Radim ; Lazar, Josef (referee) ; Macháč, Jan (referee) ; Kroutilová, Eva (advisor)
The proposed dissertation thesis contains an analysis of conditions on the boundary between layers having varied electromagnetic properties. The research is performed using consistent theoretical derivation of analytical formulas, and the underlying problem is considered also in view of multiple boundaries including the effect of the propagation of electromagnetic waves having different instantaneous speed. The author presents a survey and formulation of the basic characteristics of methods used for electromagnetic wave propagation analysis; in this respect, special emphasis is placed on radial models. The processing of the topic involved the designing and verification (using a set of different, layered planar materials) of algorithms to analyze the electromagnetic field components. The algorithm was assembled to enable simple evaluation of all components of the electromagnetic field in relation to the speed of the wave propagation in a heterogeneous environment. The proposed algorithms are compared by means of different numerical methods for the modelling of electromagnetic waves on the boundary between materials; moreover, electromagnetic field components in common points of the model were also subject to comparison. When in conjunction with tools facilitating the analysis of material response to the source of a continuous signal, the algorithms constitute a supplementary instrument for the design of a layered material. Such design enables the realization of, for example, recoilless plane, recoilless transition between different types of environment, and filters for both optical and radio frequencies.
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Dispersion relation of magnonic crystals with nontrivial spatial distribution of magnetic anisotropy
Wojewoda, Ondřej ; Hamrle,, Jaroslav (referee) ; Flajšman, Lukáš (advisor)
Magnonics is a novel field of research dealing with the physics of spin waves, which are collective excitations of a magnetization. Magnonic crystals, the basic building blocks of magnonic circuits, allow extended control over the spin-wave dispersion. The periodic structure of magnonic crystals results in the formation of a complex band structure with a gap of forbidden frequencies. Periodic structures are conventionally prepared by a local modulation of material thickness or by a step change of saturation magnetization. The presented work deals with the theoretical verification of dispersion relations of magnonic crystals, where the periodicity of the system is achieved by the modulation of the direction of uniaxial magnetic anisotropy and by continuous change of saturation magnetization. For a better insight into the propagation of spin waves in a material with non-homogeneous magnetic properties, a theory describing the refraction and reflection of spin waves at the interface is presented and further verified by numerical simulations.
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Dispersion relation of magnonic crystals with nontrivial spatial distribution of magnetic anisotropy
Wojewoda, Ondřej ; Hamrle,, Jaroslav (referee) ; Flajšman, Lukáš (advisor)
Magnonics is a novel field of research dealing with the physics of spin waves, which are collective excitations of a magnetization. Magnonic crystals, the basic building blocks of magnonic circuits, allow extended control over the spin-wave dispersion. The periodic structure of magnonic crystals results in the formation of a complex band structure with a gap of forbidden frequencies. Periodic structures are conventionally prepared by a local modulation of material thickness or by a step change of saturation magnetization. The presented work deals with the theoretical verification of dispersion relations of magnonic crystals, where the periodicity of the system is achieved by the modulation of the direction of uniaxial magnetic anisotropy and by continuous change of saturation magnetization. For a better insight into the propagation of spin waves in a material with non-homogeneous magnetic properties, a theory describing the refraction and reflection of spin waves at the interface is presented and further verified by numerical simulations.
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Analysis of an Electromagnetic Wave on the Boundary between Electromagnetic Materials
Kadlec, Radim ; Lazar, Josef (referee) ; Macháč, Jan (referee) ; Kroutilová, Eva (advisor)
The proposed dissertation thesis contains an analysis of conditions on the boundary between layers having varied electromagnetic properties. The research is performed using consistent theoretical derivation of analytical formulas, and the underlying problem is considered also in view of multiple boundaries including the effect of the propagation of electromagnetic waves having different instantaneous speed. The author presents a survey and formulation of the basic characteristics of methods used for electromagnetic wave propagation analysis; in this respect, special emphasis is placed on radial models. The processing of the topic involved the designing and verification (using a set of different, layered planar materials) of algorithms to analyze the electromagnetic field components. The algorithm was assembled to enable simple evaluation of all components of the electromagnetic field in relation to the speed of the wave propagation in a heterogeneous environment. The proposed algorithms are compared by means of different numerical methods for the modelling of electromagnetic waves on the boundary between materials; moreover, electromagnetic field components in common points of the model were also subject to comparison. When in conjunction with tools facilitating the analysis of material response to the source of a continuous signal, the algorithms constitute a supplementary instrument for the design of a layered material. Such design enables the realization of, for example, recoilless plane, recoilless transition between different types of environment, and filters for both optical and radio frequencies.
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