Magnetic properties in epitaxial binary iron and ternary iron–cobalt silicide thin films grown on Si(1 1 1)

• Published in: Journal of magnetism and magnetic materials Vol. 212; no. 3; pp. 323 - 336
• Main Authors: Berling, D, Bertoncini, P, Hanf, M.C, Mehdaoui, A, Pirri, C, Wetzel, P, Gewinner, G, Loegel, B
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2000; Elsevier Science
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Iron silicide; Magnetic properties; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magneto-optical Kerr effect; Metals. Metallurgy; Physics; Thin films; Uniaxial anisotropy; Vector magnetometry; Thin films; 75.60.Ei; Uniaxial anisotropy; Vector magnetometry; 75.70.−i; Iron silicide; 75.50.Bb; Magneto-optical Kerr effect; 75.30.Gw; Magnetic properties; Magnetization; Kerr magneto-optical effect; Ternary alloys; Ferromagnetic materials; Composition effect; Magnetic hysteresis; X-ray spectra; Experimental study; Binary alloys; Silicon alloys; Magnetic anisotropy; Magnetic circular dichroism; Cobalt alloys; Transition element alloys; Iron base alloys
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(99)00820-3

Binary Fe(Si 1− x Fe x ) iron and ternary Fe 3− y Co y Si iron cobalt silicide thin films (thickness : 200 Å) with local CsCl structure epitaxially grown at room temperature on Si(1 1 1) have been studied through X-ray magnetic circular dichroism (XMCD) and magneto-optic Kerr effect (MOKE) vector magnetometry. The binary Fe(Si 1− x Fe x ) films have ferromagnetic properties at room temperature in the range 0.09⩽ x<1 and the cobalt-substituted Fe 3− y Co y Si films are ferromagnetic as well in the whole range 0< y<3 at room temperature. The off-normal evaporation geometry leads to strong in-plane uniaxial magnetic anisotropy (including the non-epitaxial pure cobalt silicide Co 3Si) favored by the absence of orientation dependence of the fourth-order cubic term of the magnetocrystalline anisotropy energy in (1 1 1) crystallographic plane. The easy axis corresponds invariably to the direction normal to the incidence plane of the atomic flux during evaporation. The substitution of iron by silicon in Fe(Si 1− x Fe x ) films increases the coercive field but does not strongly affect the uniaxial anisotropy constant. In Fe 3− y Co y Si alloys, a similar trend is observed and the increase of coercive force may be related to defects generated by alloying. The change of the magnetic moments of Fe and Co versus y, as obtained by XMCD, can be understood in terms of simple models.