J. Phys. IV France 07 (1997) C1-317-C1-318
Magnetic Viscosity of Sr-Na-Zn W-Type Hexagonal Ferrite MagnetsH. Nishio1 and H. Yamamoto2
1 Materials Research Center, TDK Corporation, 570-2 Aza-Matsugashita, Minami-Hatori, Narita 286, Japan
2 School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki 214, Japan
The temperature dependence of the magnetic viscosity coefficient (Sv), the activation volume (v), and the anisotropy field (HA) were examined for Sr-Na-Zn W-type hexagonal ferrite magnet from 77 to 623 K. Samples with different coercive forces (HcJ) were prepared, and the dependence of Sv and von HcJ was studied at 300 K. The results show that the temperature dependence of Sv is the same as that of HcJ. The value of v is inversely proportional to HA. The logarithm of Sv is proportional to ln HcJ and HcJ is proportional to v-2.1, as in the case of Sm2Fe17Nx and SrM particles used in magnets and BaM fine particles used for high density recording media. They are considered to have a similar coercive force mechanism.
© EDP Sciences 1997