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, whichallows the selective study of the instantaneous response of atomic magnetic moments ina sample subjected to a varing magnetic field.         Mössbauer spectroscopy lines intensity depend on the relative orientationbetween the gamma ray and the atomic probe magnetic moment direction. Then, theorientation of the atomic magnetic moment can be inferred from the line intensity.Therefore, recording the line intensity as function of the applied magnetic field (MMSexperiment) 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 μmthick Amorphous Metglass 2605S2 alloy ribbons (20 mm x 10 mm) prepared by meltspinning, 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 compressivestress appears on the individual layers at temperatures different from the sputtering one,due to the layers different thermal expansion coefficients. Due to the highmagnetostriction of the amorphous phase, these stresses induce magnetoelasticanisotropy and modify the domain structure. In fact, at room temperature more than80% of the magnetic moments are aligned perpendicularly to the sample plane, while inan uncoated amorphous ribbon the magnetization mostly lays on the ribbon plane. Thetrilayer composite becomes a very soft magnetic material: a 100 Oe magnetic fieldapplied in the ribbon plane direction is enough to completely orient the magnetizationin this plane.         We have recorded the Mössbauer transmission at single Doppler energiescorresponding to the absorption maxima of the 57Fe six (broad) line Mössbauerspectrum, each one as a function of the ac magnetic field applied. The frequencyresponse 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 ribbonsFe90Zr7B3 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 propiedadesestructurales y magnéticas”, G. Pasquevich, Phd Tesis, Facultad de Ciencias Exactas, UniversidadNacional 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: AppliedPhysics, 41 (2008) 225004. DOI:10.1088/0022-3727/41/22/225004