Particle size dependence of the magnetic properties of ultrafine granular films

Authors

Sy_Hwang Liou, University of Nebraska-LincolnFollow
C.L. Chien, The Johns Hopkins University, Baltimore, Maryland

Date of this Version

April 1988

Comments

Published by American Institute of Physics. J. Appl. Phys. 63, 4240 (1988). ©1988 American Institute of Physics. Permission to use. Journal home page = http://jap.aip.org/jap/.

Abstract

Magnetic granular solids consist of ultrafine metal granules of nanometer sizes embedded in an insulating medium. The magnetic properties are dictated by the microstructure such as particle size, metal volume fraction, which are process controlled. We report the results of a series of granular Fe₆₀(SiO₂)₄₀ films in which the particle size has been systematically varied. The magnetic coercivity, ranging from 500 to 2200 Oe, increases with particle size. The ferromagnetic-superparamagnetic transition had been studied by SQUID magnetometry and Mössbauer spectroscopy. The value of the magnetic anisotropy energy is found to be much larger than that due to magnetocrystalline anisotropy.