PREPARATION AND CHARACTERIZATION OF AMORPHOUS FERROMAGNETIC THIN FILMS (LORENTZ MICROSCOPY, SAW, IRON, BORON)
Abstract
Amorphous magnetic thin films with nominal compositions of Fe(,41)Ni(,40)P(,14)B(,5) and Fe(,78)B(,22) were prepared by the dc sputtering technique. For the purpose of characterization of materials to be used for magnetic delay lines, the composition, structure, magnetic properties, electrical property, stress relief patterns and domain structures of the sputtered films are studied. An emphasis is made to clarify the magnetic domain structure of these sputtered thin films by means of the Lorentz microscopy technique. The observations showed clearly the relation between the domain structure and the strain condition of the film. In addition, the relation between the magnetic properties of the sputtered films used as delay lines and the surface acoustic wave (SAW) propagation in these films was studied. SAW delay lines were fabricated by sputtering Fe(,78)B(,22) thin films on to the LiNbO(,3) substrates. A major magnetoelastic coupling effect was found to occur below the saturation of the film when the average magnetization makes a certain angle with the direction of the stress field of the SAW. This observation is well known and the results are consistent with previous findings. Above the magnetic saturation field, considerable coupling effects continue to exist. There is a background effect which is proportional to sin('2)2(THETA), where (THETA) is the angle between the direction of magnetization and the direction of the stress field. In addition, at around 630 oe, a remarkable resonance effect was found to exist. The effect has a 2-fold symmetry with respect to (THETA) ((DBLTURN)cos('2)(THETA)). The present work is the first one to find such magnetoelastic resonance effect in amorphous films.
Degree
Ph.D.
Subject Area
Materials science
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