Magnetic properties of Ya3-xLaxFe5O12 thin films grown by a sol-gel method

Y3-xLaxFe5O12 thin films (x = 0.0, 0.5, 0.75) and powder (x = 0.0, 0.25, 0.5, 0.75 and 1.0) were fabricated by a sol-gel pyrolysis method and their magnetic properties and crystalline structures were investigated by using X-ray diffraction (XRD), atomic force microscopy, vibrating sample magnetometer (VSM), and Mossbauer spectroscopy. Films with homogeneous garnet phases were obtained from stock solutions spun on SiO2/Si (100) substrates and fired at 873-1073 K for 1 h in air. Results of X-ray diffraction show that the film had no preferred direction. The XRD patterns of Y3-xLaxFe5O12 had only peaks of the garnet structure in case of substituting the concentration x less than 0.75. Those of Y2La1Fe5O12 consisted of peaks from garnet and LaFeO3 structures. The microstructure of the films with a square shape consisted of 100-300 nm in size and 5-8 nm in surface roughness. The garnet had the largest saturation magnetization, about 34 cmu/cm(3), and the lowest coercivity, 27 Oe. (C) 2000 Elsevier Science B.V. All rights reserved.