抄録
The standard method for measuring magnetization, using a closed magnetic circuit, is inapplicable to rare earth magnet materials with very high coercivity. An open magnetic circuit method in a steady high magnetic field is therefore examined, where a correction for a demagnetizing field is important. We measured hysteresis curves for some commercial rare earth magnet materials by using cylindrical samples with various dimension ratios. The correction for the demagnetizing field gives a reasonable result for bonded magnets, whereas even the intrinsic coercivity seems to depend on the sample shape for sintered magnets. Therefore, it is necessary to reconsider the correction for the demagnetizing field and also the standard specifications of rare earth magnet materials.
