什么是 Stepwise demagnetisation？

Stepwise demagnetisation is the removal of a specimen’s remanence in steps of increasing intensity, measuring the remaining vector after each: by heating to increasing temperatures and cooling in zero field (thermal demagnetisation), which removes the components of lower blocking temperature first, or by alternating magnetic fields of increasing peak value decaying to zero (alternating-field demagnetisation), which removes those of lower coercivity first.