Magnetic viscosity in strontium ferrite fine particles

Author

Nishio, Hiroaki ; Taguchi, Hitoshi ; Hirata, Fumihiko ; Takeishi, Taku

Author_Institution

TDK Corp., Narita, Japan

Volume

29

Issue

6

fYear

1993

fDate

11/1/1993 12:00:00 AM

Firstpage

2637

Lastpage

2639

Abstract

The magnetic viscosity coefficient (S_v) and the rotational hysteresis loss (W_r) are measured for M-type hexagonal strontium ferrite (SrM) fine particles whose average diameter (D) and coercive force (H_cJ) differ. The relationship between S_v, H_cJ, the activation volume (v) and W_r is studied, together with milling effects. This experiment shows that S_v is constant and independent of the magnetic field. Ln S_v is in proportion to In H_cJ, and H_cJ ~ v^-2 could be obtained in SrM fine particles that had less milling effects. It is found that Sv increases and v decreases with SrM fine particles (D=0.3 μm) whose Wr curve increases in width with milling, even through their H_cJ significantly decreases. This can be explained as an increase in high magnetic field components of anisotropy field (H_A) caused by milling

Keywords

coercive force; ferrimagnetic properties of substances; ferrites; magnetic aftereffect; magnetic anisotropy; magnetic hysteresis; magnetic properties of fine particles; strontium compounds; activation volume; anisotropy field; coercive force; hexagonal SrFe₁₂O₁₉ ferrite fine particles; magnetic field; magnetic field components; magnetic viscosity coefficient; milling effects; rotational hysteresis loss; Ferrites; Force measurement; Loss measurement; Magnetic anisotropy; Magnetic fields; Magnetic hysteresis; Milling; Perpendicular magnetic anisotropy; Strontium; Viscosity;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.280841

Filename

280841