Study On Excitations And Properties Of Topological Spinwaves

Geometry and topology have always played an important role in physics.In recent years,topology has also entered the field of magnetism.The research of magnet and magnetism mainly focuses on the formation,stability,and manipulation of topological magnetic structures.These research results provide new physical ideas for the research of spintronics and the development of new functional devices.Compared with the non-topological magnetic configuration,the topological magnetic structure has better properties such as stability,non-volatility and controllability.In addition,because the topological magnetic structure has a high barrier characteristic in a stable state,without damaging the topological configuration,the external field strength and the temperature that used to excite spin wave have larger adjustable energy intervals,which also means the enhancement of the regulatory nature of topological spin waves.The research on the physical properties of spin wave propagation,interference,diffraction and reading and writing in topological magnetic structures under low-energy external field conditions is currently a hot spot in the field of spin wave,with profound physical significance and expected value of application.In this thesis,we analyze the microscopic origin of the magnetic topology,the interaction and the stability conditions and controllable properties of the magnetic topology,starting from the interaction Hamiltonian describing the properties of the magnetic material.Electrons that carry spins and charges are the main physical sources of magnetism in condensed materials.The formation of topological magnetic structures in magnetic materials is the result of various interactions and competition between local and cruising electrons.Magnetic Vortex and Skyrmion are two typical topological magnetic structures.The formation of these two structures is the result of exchange interaction,DM(Dzyaloshinsky-Moriya)interaction,anisotropic field,external magnetic field,dipole field and temperature.Through careful research,we have determined the basic phase diagram of magnetic Vortex and Skyrmion under the interaction of two or more fields.Based on micromagnetic simulation and preliminary experiments,the possibility of rapid and stable inversion of the polarities and chiralities of these two types of topological magnetic structures under current and magnetic fields is discussed.Secondly,on the basis of the formation of topological magnetic structure,we also studied the possible spin wave excitation modes of several topological configurations.The external magnetic field,electric field,and electric current exert different effects on the topological magnetic structure through different physical mechanisms,which stimulates various local and global spin wave modes.We found that the spin waves excited in the topological magnetic structure will carry a new class of physical freedom-orbital angular momentum.The orbital angular momentum is very robust,and its size will not decrease with the attenuation of the probability flow density.Based on the Aharonov-Casher effect,we can realize the continuous adjustment of the electric field to the intrinsic orbital angular momentum of the spin wave.The realization of the electric current/spin current regulation of the spin wave topological properties provides a new and easy-to-implement physical approach for the design and implementation of new logic devices.