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

Volume

29

Issue

6

fYear

1993

fDate

11/1/1993 12:00:00 AM

Firstpage

2602

Lastpage

2607

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;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.280851

Filename

280851