Mössbauer magnetic scans in Al/Metglas 2605S2/Al trilayers

P. MENDOZA ZÉLIS; G. A. PASQUEVICH; P. S. MOSCON; E. C. PASSAMANI; F. H. SÁNCHEZ

Manizales

Workshop; IX Latin American Workshop on Magnetism, Magnetic Materials and Their Applications; 2010

Universidad Nacional de Colombia in Manizales

During the last 10 years we have been developing the Mössbauer Effect Scan (MES) technique which it was applied it to several problems in materials physics [1, 2]. One of the MES methologies is the Mössbauer Magnetic Scan (MMS) one, which allows the selective study of the instantaneous response of atomic magnetic moments in a sample subjected to a varing magnetic field.Mössbauer spectroscopy lines intensity depend on the relative orientation between the gamma ray and the atomic probe magnetic moment direction. Then, the orientation of the atomic magnetic moment can be inferred from the line intensity. Therefore, recording the line intensity as function of the applied magnetic field (MMS experiment) is possible to study local and dynamic magnetic properties of the material.In this work we have applied this technique to the study of 20 μm thick Amorphous Metglass 2605S2 alloy ribbons (20 mm x 10 mm) prepared by melt spinning, which were coated on both sides with 20 μm aluminum by DC sputtering [3].We have found that in this type of trilayers, important tensile or compressive stress appears on the individual layers at temperatures different from the sputtering one, due to the layers different thermal expansion coefficients. Due to the high magnetostriction of the amorphous phase, these stresses induce magnetoelastic anisotropy and modify the domain structure. In fact, at room temperature more than 80% of the magnetic moments are aligned perpendicularly to the sample plane, while in an uncoated amorphous ribbon the magnetization mostly lays on the ribbon plane. The trilayer composite becomes a very soft magnetic material: a 100 Oe magnetic field applied in the ribbon plane direction is enough to completely orient the magnetization in this plane.We have recorded the Mössbauer transmission at single Doppler energies corresponding to the absorption maxima of the 57Fe six (broad) line Mössbauer spectrum, each one as a function of the ac magnetic field applied. The frequency response was studied using a triangular Magnetic field wave, from 7mHz to 80 kHz, and using amplitudes of 1100 y 65 Oe, respectively.[1] “Determination of the Iron atomic magnetic moments dynamics in the nanocrystalline ribbons Fe90Zr7B3 by Mössbauer Magnetic Scans”, G. A. Pasquevich, P. Mendoza Zélis, F. H. Sánchez, M. B. Fernández van Raap, A. L. Veiga and N. Martinez, Physica B, 384, (2006) pp 348-350. ISSN 0921-4526.[2] "Desarrollo de la técnica Barridos de efecto Mössbauer. Aplicación al estudio de propiedades estructurales y magnéticas”, G. Pasquevich, Phd Tesis, Facultad de Ciencias Exactas, Universidad Nacional de la Plata, March 2008.[3] “Magnetic domain structure and Anisotropy distribution in Al/Metglas 2605S2/Al trilayers”, P. S. Moscon, E. C. Passamani, C. Larica, F. H. Sánchez and P. Mendoza Zélis. Journal of Physics D: Applied Physics, 41 (2008) 225004. DOI:10.1088/0022-3727/41/22/225004