國 Material magnetized to saturation by Magnetization alignment of domains. of material M When driving magnetic field drops to zero,the ferromagnetic materia retains a considerable degree of The material follows a non-linear magnetization.This is useful as a magnetization curve when magnetic memory device. magnetized from a zero field value. 第七章磁介质 Applied magnetic 母H field intensity The driving magnetic field must be reversed and increased to a large value to drive the magnetization to The hysteresis loop shows the "history zero again. dependent"nature of magnetization of a 图 ferromagnetic material.Once the material has been driven to saturation, the magnetizing field can then be Toward saturation in dropped to zero and the material will the opposite direction retain most of its magnetization (it remembers its history).第七章 磁介质