Anomalous magnetic viscosity in bulk-amorphous materials

Abstract

The demagnetization processes and the magnetic viscosity have been studied on a bulk-amorphous Nd60Fe30Al10 rod at room temperature. Many unique magnetic properties have been found in this novel hard magnetic material. A clear hysteresis was present on the minor loops, though the total and irreversible susceptibilities exhibited single-phase magnet behavior. A significant magnetic viscosity was evident at positive fields. A large magnetic viscosity was found at negative fields close to the coercivity. The time-dependent magnetization curves were not logarithm-linear and could be well fitted with a logarithm power series with N = 6. The fluctuation field was strongly dependent on the magnetic field. The activation volume was calculated to be 15-60×10-18 cm3. The magnetic viscosity on the minor loops was measured. A non-monotonic behavior was found.