Properties Of Interface Spin Waves In Bilayer Magnetic Thin Films

In this paper,we study the spin spectra,spin wave density of states and the spatial distribution of spin waves in symmetric and asymmetric bilayer magnetic thin films with eight atomic layers(layer A and B are both composed of four atomic layers)by using the quantum statistical Green’s function and the Heisenberg model method.The effects of external physical factors and interface properties on the occupied area and frequency of interface spin waves in two-dimensional Brillouin zone are investigated.For the symmetric bilayer magnetic thin film,there are two interface spin wavesω-1 andω-2 on each interface layer(the fourth and fifth atomic layers).With the increase of temperature,the occupied area of the two interface spin waves in the Brillouin zone increases first and then decreases,and the frequency of the two interface spin waves decreases.With the increase of the external magnetic field,the occupied area of the two interface spin waves in the Brillouin zone decreases,and the frequency of the two interface spin waves increases.When the interface interlayer exchange coupling,the interface intralayer exchange coupling and the interface anisotropy increase,the occupied area of the two interface spin waves in the Brillouin zone decreases,and the frequency of the two interface spin waves increases.There are two interface spin waves in the middle temperature region,and only one interface spin wave in the low temperature region and the high temperature region.When the external magnetic field,the interface interlayer exchange coupling,the interface intralayer exchange coupling and the interface anisotropy are relatively small,there are two interface spin waves.When the parameters are relatively large,only one interface spin wave exists in the symmetric bilayer magnetic thin film.For the asymmetric bilayer magnetic thin film,there is only one interface spin wave on each interface layer,the interface spin wave of the fourth atomic layer isω-4,and the interface spin wave of the fifth atomic layer isω-5.With the increase of temperature,the occupied area of the two interface spin waves in the Brillouin zone increases first and then decreases,and the frequency of the two interface spin waves decreases.With the increase of the external magnetic field,the occupied area of the two interface spin waves in the Brillouin zone decreases,and the frequency of the two interface spin waves increases.When the interface interlayer exchange coupling,the interface intralayer exchange coupling and the interface anisotropy increase,the occupied area of the interface spin waveω-4 in the Brillouin zone increases gradually,while the occupied area of the interface spin waveω-5 in the Brillouin zone decreases gradually,and the frequency of the two interface spin waves increases.The temperature,the external magnetic field,the interface intralayer exchange coupling and the interface anisotropy have great influence on the frequency of the interface spin waveω-5.However,the interface interlayer exchange coupling has a strong influence on the frequency of the interface spin waveω-4.There are two interface spin wavesω-4 andω-5 in the middle temperature region,and only one interface spin waveω-5in the low temperature region and the high temperature region.When the external magnetic field is small,there are two interface spin wavesω-4 andω-5,but only one interface spin waveω-5exists in the larger external magnetic field.When the interface interlayer exchange coupling and the interface intralayer exchange coupling are small,there is only one interface spin waveω-5.When the interface interlayer exchange coupling and the interface intralayer exchange coupling become large,there are two interface spin wavesω-4 andω-5.The innovation of this paper is as follows:the effect of temperature on the properties of interface spin waves is studied,and it is found that the source of the interface spin wave is the difference between the interface properties and the inner layer properties of the thin film.The contents of this paper enrich the study of interface spin waves in magnetic thin films,and provide a richer theoretical basis for the research of microwave devices based on magnetic thin films.