Title :
Magnetism in ultrafine Fe and Co particles
Author :
Gangopadhyay, S. ; Hadjipanayis, G.C. ; Sorensen, C.M. ; Klabunde, K.J.
Author_Institution :
Dept. of Phys. & Astron., Delaware Univ., Newark, DE, USA
fDate :
11/1/1993 12:00:00 AM
Abstract :
The magnetic properties of vapor deposited Fe and Co particles in the size range of 50-350 Å are studied. Magnetization, Mossbauer and structural data show a core-shell morphology, where the core is metallic and the shell is a polycrystalline Fe (Co)-oxide. A sharp reduction in magnetization is observed in particles with a size below 100 Å. This is attributed to surface/interface spin canting brought about by the ferrite oxide shell. The effect of various surface chemistries on the hysteretic behavior is systematically studied. The results clearly indicate that the oxide shell controls both the magnitude and the temperature dependence of coercivity
Keywords :
Mossbauer effect; cobalt; coercive force; ferromagnetic properties of substances; iron; magnetic hysteresis; magnetic properties of fine particles; passivation; vapour deposited coatings; 50 to 350 Å; Co-CoO-Co3O4; Fe-Fe2O3-Fe3O4; Mossbauer data; coercivity; core-shell morphology; ferrite oxide shell; hysteretic behavior; magnetic properties; magnetization; magnitude; metallic; polycrystalline Co oxide; polycrystalline Fe oxide; structural data; surface chemistries; surface/interface spin canting; temperature dependence; vapour deposited Co particles; vapour deposited Fe particles; Chemistry; Ferrites; Hysteresis; Iron; Magnetic cores; Magnetic properties; Magnetization; Surface morphology; Temperature control; Temperature dependence;
Journal_Title :
Magnetics, IEEE Transactions on
