Surface Domain Configuration of Nd-Fe-B Sintered Magnets Influenced by Underneath Magnetization

The influence of underneath magnetization of Nd-Fe-B sintered magnets on surface domain configurations was investigated using a Kerr microscope by cutting the magnets at an angle to the c-axis. When the angle formed by the surface and the c-axis is larger than 30 degrees, the observed domain configurations change to maze patterns because of an increase in the demagnetizing field at the surface. In contrast, when the cutting angle is 10 degrees, residual magnetization increases with the applied field. It was found that at a cutting angle of 10 degrees, the underneath domain configurations can be indirectly observed through the surface by propagation of magnetic flux from the underneath grains.