Title :
Magnetic viscosity in strontium ferrite fine particles
Author :
Nishio, Hiroaki ; Taguchi, Hitoshi ; Hirata, Fumihiko ; Takeishi, Taku
Author_Institution :
TDK Corp., Narita, Japan
fDate :
11/1/1993 12:00:00 AM
Abstract :
The magnetic viscosity coefficient (Sv) and the rotational hysteresis loss (Wr) are measured for M-type hexagonal strontium ferrite (SrM) fine particles whose average diameter (D) and coercive force (HcJ) differ. The relationship between Sv, HcJ, the activation volume (v) and Wr is studied, together with milling effects. This experiment shows that Sv is constant and independent of the magnetic field. Ln Sv is in proportion to In HcJ, and HcJ ~ 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 HcJ significantly decreases. This can be explained as an increase in high magnetic field components of anisotropy field (HA) 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;
Journal_Title :
Magnetics, IEEE Transactions on
