Title :
The relationship between structure and magnetic properties in nanostructured FePd ferromagnets
Author :
Okumura, Hideyuki ; Soffa, William A. ; Klemmer, Timothy J. ; Barnard, J.A.
Author_Institution :
Dept. of Mater. Sci. & Eng., Pittsburgh Univ., PA, USA
fDate :
7/1/1998 12:00:00 AM
Abstract :
FePd L10 ferromagnets with ultra-fine microstructures (submicron/nanoscale) have been studied. The powders and thin films with nanoscale microstructure were produced using high energy ball milling and vacuum sputtering, respectively. These ultra-fine grained materials were characterized using TEM, SEM, and X-ray diffraction. The line broadening method was used to estimate the crystallite size and lattice strain of the ball milled powders with the aid of TEM observation. The magnetic properties of the epoxy-bonded powders, isostatically pressed pellets and the thin films were measured using a vibrating sample magnetometer (VSM). The enhanced coercivities exhibited by these ferromagnets compared to bulk materials are discussed in terms of the mechanism of magnetization reversal operating in these fine-particle aggregates and thin films in the grain size range of D<Dc but well above the superparamagnetic regime. Micromagnetic analysis is applied to discuss the mechanism of coercivity, and a “pinning” model is proposed in these so-called “interaction” domain ferromagnets
Keywords :
X-ray diffraction; coercive force; crystal microstructure; crystallites; ferromagnetic materials; iron alloys; magnetic particles; magnetic thin films; magnetisation reversal; nanostructured materials; palladium alloys; scanning electron microscopy; sputtered coatings; superparamagnetism; transmission electron microscopy; FePd; FePd L10 ferromagnets; SEM; TEM; TEM observation; X-ray diffraction; ball milled powders; coercivities; coercivity; crystallite size; epoxy-bonded powders; ferromagnets; fine-particle aggregates; grain size; high energy ball milling; interaction domain ferromagnets; isostatically pressed pellets; lattice strain; line broadening method; magnetic properties; magnetization reversal; micromagnetic analysis; nanoscale microstructure; nanostructured FePd ferromagnets; powders; structure; superparamagnetic regime; thin films; ultra-fine grained materials; ultra-fine microstructures; vacuum sputtering; Ball milling; Coercive force; Crystalline materials; Elementary particle vacuum; Magnetic materials; Magnetic properties; Microstructure; Powders; Sputtering; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
