MAGNETIC VISCOSITY OF NANOCOMPOSITE Sm-Fe-Cu-Zr-Ga-C RIBBONS

The magnetic viscosity was investigated at temperatures between 100 and 293 K for the nanocomposite Sm₂Fe_18.25Zr_0.25Cu_0.5Ga₂C₂ ribbons prepared by melt-spinning and subsequent annealing. It was found that the maximum S and \chi_irr, located near coercivity, increase with increasing temperature. The viscosity parameter S_v was found to be strongly dependent on the applied fields at lower fields than the coercivities. The relation between S_v and coercivity was analyzed. The coercivity mechanism is mainly controlled by domain-wall pinning. The activation volume associated with magnetization reversal, which can be calculated from S_v, is much smaller than the grain volume.