Temperature dependence of the magnetization of ultrafine particles of nickel

Author

Li, Hua ; Gong, Wei ; Liu, Shuqing ; Shi, Guoshun

Author_Institution

Inst. of Phys., Chinese Acad. of Sci., Beijing, China

Volume

28

Issue

5

fYear

1992

fDate

9/1/1992 12:00:00 AM

Firstpage

3177

Lastpage

3179

Abstract

Partially oxidized Ni ultrafine particles were prepared by the gas evaporation method, and the magnetization of the particles has been measured between 1.5 and 250 K in applied fields up to 15 kOe. The results are well described by spin-wave theory (SW) and Stoner excitement (SE) above a characteristic temperature T_s which depends on the sizes of particles. Discrepancy of the data from SW and SE below T_s was associated with the superparamagnetism of antiferromagnetic NiO particles on the surface of ferromagnetic Ni particles. For temperatures above T_s, the spin-wave constants B were found to be 2.83×10^-6 K^-3/2 and 2.60×10^-6 K^-3/2 for particles with average diameters of 100 Å and 220 Å, respectively

Keywords

ferromagnetic properties of substances; magnetic properties of fine particles; magnetisation; nickel; oxidation; particle size; spin waves; superparamagnetism; 1.5 to 250 K; Ni ultrafine particles; Stoner excitement; antiferromagnetic NiO particles; characteristic temperature; ferromagnetic particles; gas evaporation; magnetization; partial oxidation; spin-wave constants; spin-wave theory; superparamagnetism; temperature dependence; Kelvin; Magnetic field measurement; Magnetic materials; Magnetization; Nickel; Particle measurements; Physics; Temperature dependence; X-ray diffraction; X-ray imaging;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.179750

Filename

179750