Abstract:A new interference effect has been observed in the transmission of microwave signals through Permalloy films. This effect, which involves interference between the eddy-current microwave transmission and the magnetic field associated with the excited spin waves, permits identification of the symmetry and surface pinning behavior of the standing spin waves. Previous studies of spin waves in Permalloy films have involved a determination of the surface impedance in the vicinity of spin-wave excitation. The present… Show more
Several publications have been devoted to the study of standing spin waves in thin ferromagnetic conducting plates. The exciting microwave field is very often considered as constant on the width of the plates, then propagation effects are disregarded. Here, on the contrary, it is shown that it is a complex electromagnetic problem in the most general case from the coupling of electromagnetic and spin waves. Thus it is possible to find theoretically the main experimental results obtained on thin nickel films, and particularly to indicate the effect, the sign, and the value of the surface anisotropy constant on each side of the plates.Plusieurs publications ont 6th consacrbes B I'btude des ondes de spin stationnaires dans des lames minces conductrices ferromagnbtiques. Le champ hyperfrkquence excitant est trhs souvent considbrb comme uniforme sur 1'8paisseur des lames, les phbnombnes de propagation sont ainsi nbgligbs. Nous montrons qu'il s'agit, au contraire, d'un problbme d'blectromagnbtisme tres blaborb que nous essayons de poser dans sa plus grande gbnbralitb B partir du couplage des ondes blectromagnbtiques et des ondes de spin. Nous avons ainsi la possibilitb de trouver thboriquement les principaux rbsultats expbrimentaux obtenus sur des lames de Nickel et de prbciser, en particulier, le rdle, le signe et la valeur des constantes d'anisotropie de surface sur chacune des faces des lames.
Several publications have been devoted to the study of standing spin waves in thin ferromagnetic conducting plates. The exciting microwave field is very often considered as constant on the width of the plates, then propagation effects are disregarded. Here, on the contrary, it is shown that it is a complex electromagnetic problem in the most general case from the coupling of electromagnetic and spin waves. Thus it is possible to find theoretically the main experimental results obtained on thin nickel films, and particularly to indicate the effect, the sign, and the value of the surface anisotropy constant on each side of the plates.Plusieurs publications ont 6th consacrbes B I'btude des ondes de spin stationnaires dans des lames minces conductrices ferromagnbtiques. Le champ hyperfrkquence excitant est trhs souvent considbrb comme uniforme sur 1'8paisseur des lames, les phbnombnes de propagation sont ainsi nbgligbs. Nous montrons qu'il s'agit, au contraire, d'un problbme d'blectromagnbtisme tres blaborb que nous essayons de poser dans sa plus grande gbnbralitb B partir du couplage des ondes blectromagnbtiques et des ondes de spin. Nous avons ainsi la possibilitb de trouver thboriquement les principaux rbsultats expbrimentaux obtenus sur des lames de Nickel et de prbciser, en particulier, le rdle, le signe et la valeur des constantes d'anisotropie de surface sur chacune des faces des lames.
This note investigates the nature of the main peak in spin wave resonance ( S W ) spectra of films. Authors variously attribute the main peak to one of the three types of spin waves: 1. a non-uniform space mode (k # 0), 2. the uniform mode (k = 0 ) , 3. the surface mode k = it ( t (real) # 0), but physical conditions for a unique co-ordination are as yet undefined. Thus, the uniform peak i s though to occur 1. at parallel configuration ( 4 = - Experimentally, spin wave types in SWR are indentified by following the shift in resonance peak as the film thickness is taken smaller and smaller; then 1. non-uniform space mode peaks shift towards weaker fields; 2. the uniform mode peak is unshifted; 3. the surface mode peak shifts towards stronger fields (contrary to nonuniform space mode peaks) by an amount which, for thicker films (above a critical thickness in the range 10 to 10 8 dependent on the surface anisotropy value) if3 practically imperceptible so that the surface peak is now unshifted (like the uniform mode peak!) (Puszkarski (7 to 9), Sokolov et al. (10, 11)).
3This behaviour can cause mistakes in determining the nature of the main peak in thick films by the method of thickness variation as, it seems, was the case in some of the above-mentioned experiments. It is thus necessary to have a supplementary criterion for distinguishing between the uniform and surface peak. The following statement can be helpful: 1. The uniform mode resonance peak appears in thin films only at the critical configuration 4 as a single resonance. 2. In multi-peak crit
This paper describes a two-cavity microwave transmission experiment, carried out at a frequency of 35 GHz and a temperature of 4.2°K. A resonant transmission signal has been observed through thin sheets of the ferromagnetic metals permalloy and nickel when placed as the common end wall of the two TE110 cavities. The transmitted signal occurs at an external magnetic field value appropriate to the antiresonance condition. It is better defined for the Permalloy sheets, due to the smaller line-width, and in this case the resonance line shows a structure which is associated with an interference effect between electromagnetic waves and spin waves. A general theory of microwave transmission in ferromagnets is briefly presented, which includes spin-wave and boundary condition effects, and an indication is given of the origin of the structure observed in this experiment as well as of further effects to be expected in experiments of this type.
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