Amorphous Soft Magnetic Material Formation by Ion Mixing
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AMORPHOUS SOFT MAGNETIC MATERIAL FORMATION BY ION MIXING P. GERARD a), G. SURAN b), B. BLANCHARD c), J. DEVENYI d), M. DUPUY, d) and P. MARTIN a) a) L.E.T.I-C.E.A. 85 X, 38041 Grenoble (F), b) Laboratoire de Magn6tisme C.N.R.S. (92195) Meudon Principal CEDEX, c) DERDCA-CEA 85 X, 38041 Grenoble (F), d) LEPES-C.N.R.S. 166 X, 38041 Grenoble (F) ABSTRACT ion mixing of FeNi-Si multilayers is performed at the same dose of 3.101t5 Xe+ cm- 2 with either of the three energies 200, 300 or 400 keV. The irradiation is done at liquid nitrogen temperature (LNT) or at room temperature (RT). The mixed layers are characterized by reflection high energy electron diffraction (RHEED), transmission electron microscopy (TEM), Rutherford backscattering (RBS), secondary ion mass spectroscopy (SIMS) and ferromagnetic resonance (FMR). Films made at 400 keV are more reproducible and as homogeneous as the best amorphous films realized up to now, using sputtering techniques. INTRODUCTION Transition metal-metalloid amorphous soft magnetic alloys are at the origin of many investigations as much for a fundamental standpoint [1] as for numerous technological applications [2]. The theoretical approach is to look at the influence of the amorphous structure on the different magnetic parameters such as the magnetization (47Ms), the Curie temperature (Tc), the anisotropy, etc., and their respective temperature dependence. Some of the amorphous soft magnetic materials have already found their use for certain applications, (e.g., transformers) because they have lower losses, lower coercivities, higher permeabilities, and are competitive in cost with some of their crystalline counterparts. There is in the literature much experimental data on the properties of these materials prepared by various techniques. Up to now, thin layers have only been made through coevaporation or sputtering and both have their advantages and their drawbacks. Here we propose the use of an ion mixing method, recently developed at Caltech [3], in order to make (Fe 2 0 Ni8O)1OO-xSix amorphous films, and to analyze by FMR the influence of certain irradiation parameters on the magnetic properties of these mixed layers. Indeed, magnetic measurements of amorphous transition metal-metalloid alloys are very sensitive to small variations of chemical composition and in depth homogeneity. Consequently such a system is particularly well adapted for the measurement of the ion mixing efficiency. The choice of the Permalloy composition (Fe 2 0 Ni8 o) as a starting material was made so as to have a final amorphous product, after the addition of the glass former dilutent Si, with no magnetostriction and little or no anisotropy. Under these circumstances, FMR spectra permit a straight-forward interpretation of the information giving access directly to 4NMs, the g factor, and Tc, and also permit the use of this method at low temperature on account of the narrow character of the resonance linewidth. The temperature dependence of the magnetic behaviour of certain of these layers has been studied elsew
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