Eddy Current Effects and Pinning Effects in Fe and Ni Single Crystals With Low Defect Densities

Effects of eddy currents and pinning due to dislocations on domain wall movement have been studied for single crystals of Fe and Ni metals using scaling rules in magnetic minor hysteresis loops. The minor-loop coefficients, obtained from power-law rules between the amplitude dependent parameters, increase due to plastic deformation at room temperature in both metals. However, the temperature dependence is quite different from each other. While for Fe metal the coefficients are almost constant above T = 200 K and increase remarkably with decreasing temperature below T = 200 K, the coefficients for Ni metal increase around T = 430 K, take a maximum, and abruptly decrease with decreasing temperature. The remarkable increase of the coefficients below T = 200 and 430 K observed in nondeformed Fe and Ni metals, respectively can be explained by the eddy current effects associated with the increase in electrical conductivity at low temperatures. On the other hand, for deformed Ni metal where the pinning effect is dominant, the maximum of the coefficients can be explained as being due to the temperature dependence of the magneto-crystalline anisotropy and magneto-striction.