Structural and magnetic properties of TM–SiO2 (TM = Fe, Co, Ni) films

• Published in: Journal of magnetism and magnetic materials Vol. 262; no. 1; pp. 102 - 106
• Main Authors: Socolovsky, L.M, Denardin, J.C, Brandl, A.L, Knobel, M, Zhang, X.X
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2003; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Fine-particle systems; Magnetic nanoparticles; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of nanostructures; Magnetic properties of surface, thin films and multilayers; Magnetic thin films; Physics; SAXS; Small particles and nanoscale materials; Studies of specific magnetic materials; 75.50.Tt; Magnetic thin films; Magnetic nanoparticles; 73.63.Bd; 75.75.+a; SAXS; Particle size; Inorganic compounds; Magnetization; Transition element compounds; Hall effect; Iron; XRD; Small angle X ray scattering; Experimental study; Cobalt; 75.10.Tt; Thin films; Nanoparticles; 75.75. + a Magnetic thin films; Quantity ratio; Transmission electron microscopy; Silicon oxides; Percolation; Nickel; Magnetoresistance
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(03)00028-3

TMx–(SiO2)1−x (TM=Fe, Co, Ni) thin films were prepared in a wide concentration range (0.35 ⩽x⩽1). Structure was studied with transmission electron microscopy (TEM), X-ray diffraction (XRD) and small angle X-ray scattering (SAXS). Magnetic and magnetotransport properties were investigated by means of magnetization and Hall effect measurements. TEM images display nanometric spherical structures embedded in a SiO2 amorphous matrix, with typical sizes increasing from 3 to 5nm when TM volume concentration x is increased. SAXS measurements indicate a complex structure formed by nanosized objects. XRD measurements show that the structure is composed by amorphous SiO2 and TM crystallites. Slightly above the percolation threshold all samples display giant Hall effect. The observed magnetic properties are dependent on x, and display an evolution resulting from the progressive increase of the mean particle size.