| The spin wave is a collective effect of the spins. It is a very important physical quantity of the material magnetism. The spin wave excitation is a useful method. So the spin wave excitations is an attractive topic in physical fields. The microcosmic mechanism is an interior matter and a theoretical foundation of the spin wave excitations. The magnetic field is essential to the spin wave excitations. There are much attention focused on magnetic field paralleling z-axis (the spontaneous magnetization's direction) while the transverse magnetic field is usually ignored. This thesis emphasized on the effect of the transverse magnetic field. Firstly, by applying harmonic oscillator wave function of the spin wave and the usual equation of the magnetization motion, a principle of the spin wave's even excitations was fond. Secondly, we put the magnetic field on x-y plane (called the transverse magnetic field) and made the magnetic field uniform revolve with z-axis, we only consider the surface of sample without spin pinning, the spin wave function could be expressed as the form of the sine function, In the case of the assume condition, we could changed the angle into the displacement, which is the spin wave of km (wave vector) walk paralleling z-axis. The expression isθ=αkm z,αis the factor of the frequency ratio. Not only the results from Kittel's theory computation but some new results through LL equation was obtained. If am satisfy certain qualifications by choosing the proper value ofαand the quantum number m, the spin wave excitations can be controlled.
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