INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
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Magnetoelastic effect and anisotropy distribution in Al/METGLAS 2605S2/Al trilayers studies by Mössbauer Spectroscopy
P.S. MOSCON; E.C. PASSAMANI; F.H. SÁNCHEZ; C. LARICA; P. MENDOZA ZÉLIS; A. Y. TAKEUCHI
Conferencia; International Conference on the Applications of the Mössbauer Effect; 2009
Soft magnetic melt-spun amorphous ribbons still attract special attention of the scientific community due to the fact that these materials pose fundamental questions not yet clarified and also because of their potential for technological application in electronic devices such as transformer cores, small motors, and specially as sensing elements [1,2].Bimetal sensing devices are usually produced by gluing surfaces of different metal layers. It is considered, in general, that the adhesive material does not play any important role for induction of mechanical stress when the device temperature is changed or when stress is applied on the device. This relative simple set-up has some advantages (cheaper to be produced), but it leads to technical inconveniences because the adhesive is a third material and certainly influences the device properties. In general, the mechanical coupling of the bimetal glued surfaces is weak compared with that obtained if the metal surfaces are homogeneously coupled (as occurs when deposition techniques are used), which may reduce the magnitude of the desired magnetoelastic effect. In this work, Al coatings, with thickness (x) up to 20 μm, were deposited by dc sputtering on both sides of the Metglas 2605S2 precursor melt-spun ribbons. Spin reorientation, induced by the magnetoelastic effect, was clearly observed in the Al/Metglas 2605S2/Al trilayers by monitoring the 2 and 5 line intensities of the Mössbauer spectra obtained at different temperatures. The average spin orientation angles can be controlled by adjusting the Al thickness, as shown in Fig. 1. A magneto-mechanical coefficient, which measures the rate of spin reorientation with respect to the temperature variation, was obtained and it is found to be equal to −0.15° K−1 and −0.28° K−1 for x = 5 μm and 20 μm, respectively. Using a spin structure phenomenological model, in-plane native magnetic anisotropies ranging up to 3 kJ m−3 were estimated for the Metglas 2605S2 ribbons. Energy anisotropy values higher than 20 kJ m−3 are associated with inhomogeneities and defects from the sample preparation method and may correspond to about 10% of the ribbon volume. In addition, for 20 μm Al thickness,changes in the 57Fe atoms charge density (central shift of Mössbauer spectra) has been also observed, as displayed in Fig. 2 . M. E. McHenry, M. A. Willard and D. E. Laughlin, Prog. in Mat. Sci., 44 (1999) 291. E. Kaniusas, L. Mehnen, C. Krell and H. Pfüzner, J. Magn. Magn. Mater., 215 (2000) 776.