Investigation on negative refract of magnetic metamaterials

Abstract

Manipulation of electromagnetic response of materials provides a newlinepowerful means of controlling the interaction between light and matter. Negative newlinerefraction is one of the signature effects of metamaterial Physics and its exciting newlinedemonstration became a frontier for material and electromagnetic research. newlineThe dramatic Physics exhibited by the metamaterial is underpinned by the newlineresonant response of the metamolecules. A wide range of tunable terahertz newline(THz) resonance frequency provides a technological breakthrough in newlinemetamaterials. Most metamaterial so far designed have been based on newlinecomplicated resonant elements such as split rings and hyperbolic metamaterials. newlineUnfortunately, magnetic response of most of the materials tails off at higher newlinefrequencies. Higher frequency excitation in metamaterials requires more newlinecomplicated designs or toroidal moment. Interestingly the toroidal excitations newlineare naturally maintained in some magnetic quasi structures such as magnetic newlinevortices and make it suitable for THz resonances. Magnetism and left-handed newlinebehavior are two extreme phenomena that do not seem to be compatible and the newlinecoexistence of both cooperative effects was not foreseen. Terahertz spintronics is newlinean emerging field that bridges the boundary between magnetism and photonics, newlinewhich make the magnetic material suitable for photonic applications. The work newlinepresented in thesis aims at the design and the study of negative permeability newlineproperty in naturally occurring magnetic materials. Here, we present a theory on newlinethe high frequency negative permeability resulting from THz spin wave newlineresonances in two dimensional arrays of magnetic swirling structures and in newlineartificial spin ices. Numerical and analytical approaches are used to demonstrate newlineTHz negative refraction and the mechanisms that allow such structures to newlineproduce the excitation of electromagnetic resonances. newline newline newline