Electromagnetic Wave Propagation In Low-Dimensional Electrically Insulating Ferromagnetic Media Physics

Ferrite materials,especially ferrite microwave ferrite devices,have been widely used in many high-tech fields for more than half a century because of their unique magnetic and electrical properties（such as high resistivity,high magnetic permeability,moderate saturation magnetization,moderately high dielectric constant,and excellent thermal stability）.In the past two decades,researchers have constructed a series of Kraenkel-Manna-Merle（KMM）systems to study the microwave propagation behavior in ferrite media,which are of importance in explaining and predicting nonlinear phenomena occurring in ferrite materials.In this paper,based on（1+1）-dimensional KMM system,（1+1）-dimensional Generalized Kraenkel-Manna-Merle（GKMM）system and（2+1）-dimensional KMM system,the propagation modes of electromagnetic waves in a low-dimensional ferrite media are theoretically studied.Besides,some numerical simulations are performed to investigate the effects of Gilbert-damping and inhomogeneous exchange on the propagation of short waves in ferrite films.Firstly,the（1+1）-dimensional KMM system and its applicable conditions are derived.The Consistent Tanh Expansion（CTE）method is applied to the（1+1）-dimensional KMM system,some interaction solutions such as the breather solution,the oscillatory soliton solution and the instantaneous solution are obtained.On the other hand,the rogue wave solutions of the（1+1）-dimensional KMM system are constructed by the Painlevétruncation expansion method,and the interaction of the rogue wave solution with multi-solitons are studied in details,including the butterfly-type interactions,the X-type and the Y-type interactions,etc.In addition,we construct some analytical solutions of the（1+1）-dimensional damped KMM system via the CTE method.Some analytical solutions of the（2+1）-dimensional KMM system are discussed.Secondly,further studies are carried out to investigate the effects of Gilbert damping and inhomogeneous exchange on electromagnetic wave propagation in ferrite films.We resort to numerical methods because of the integrability of the equation.The approximate solutions are constructed by the Hirota method.Starting from these approximate solutions,four aspects are studied in this thesis:（I）.Transmission stability of multi-loop-solitons.it is observed that the magnetic solitons are stable if the velocity V>0 and unstable for V<0.（II）.The influence of Gilbert damping on the propagation of multi-loop-solitons.The results show that the Gilbert-damping only acts on reducing the amplitude and velocity of solitons during propagation.The amplitude attenuation with time indeed has the form A（t）=A₀ exp（-2st/3）against A（t）=A_0·exp（-st）in the linear theory,which is related to the nonlinear effect.（III）.The effects of inhomogeneous exchange processes on multi-loop-solitons transmission are studied.Such effects depend on the frequency of solitons and inhomogeneous exchange coefficient of the materialwe.In different situations,the amplitude of the loop soliton will oscillate or diffract along the x-axis with time.These amplitude change behaviors are classified into four categories,which are described by the（ω-ρ）area graph,the typical propagation figure of each category is presented.（IV）.Further investigations have been carried out to polycrystalline ferrites that take both Gilbert damping and inhomogeneous exchange process into account.