磁振子宏观效应以及热扰动场对反磁化的影响  

Macroeffect of magnons and thermal fluctiation on magnetization reversal

作　　者：李柱柏 魏磊 张震 段东伟 赵倩 Li Zhu-Bai;Wei Lei;Zhang Zhen;Duan Dong-Wei;Zhao Qian(School of Materials and Metallurgy,Inner Mongolia University of Science and Technology,Baotou 014010,China;School of Science,Inner Mongolia University of Science and Technology,Baotou 014010,China)

机构地区：[1]内蒙古科技大学材料与冶金学院,包头014010 [2]内蒙古科技大学理学院,包头014010

出　　处：《物理学报》2022年第12期369-373,共5页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2021YFB3500100);国家自然科学基金(批准号:51861030);内蒙古自治区自然科学基金(批准号:2020MS01007);内蒙古自治区高等学校创新团队发展计划(批准号:NMGIRT2215)资助的课题。

摘　　要：热扰动导致的磁反转是越过能量势垒的不可逆反转,称为热助隧穿.本文研究Pr-Fe-B磁体热扰动导致的磁反转弛豫现象,反转磁矩与时间自然对数关系可表示为与能垒之间的关系,因此反磁化弛豫现象可用磁振子按能量的玻色统计分布率来解释,是磁振子宏观效应的体现.反磁化不可逆过程的临界尺寸为纳米级,与理论磁畴壁尺寸接近,证实热扰动反磁化经过磁畴壁形核去钉扎过程.在实空间反磁化耦合体积增大能减小磁振子隧穿的反磁化概率,热扰动场减小;热扰动后效场测量值与热扰动场计算值基本是一致的.温度升高,热扰动能量增大,由于耦合作用热扰动后效场有所减小,但热扰动后效场相对于矫顽力的作用增大.The magnetization reversal resulting from the thermal fluctuation is irreversible for overcoming the energy barrier, ant it is called the thermally assisted tunneling. In this paper the relaxation in magnetizaition reversal resulting from the thermal fluctuation is observed in Pr-Fe-B permanent magnet. The dependence of magnetic moment on the time natural logarithm is the same as that on the energy barrier in the thermally assisted tunneling. So the relaxation in magnetization reversal originates from the macroeffect of magnons which follow Bose distribution law. The critical size in the irreversible magnetization reversal obtained by the fluctuation field is on a nanometer scale and close to the theoretical domain wall size, indicating that the thermally assisted magnetization reversal undergoes the nucleation and de-pinning of domain wall. The increase of coupling volume will reduce the possibility of magnons tunneling in magnetization reversal due to the weakening effect of thermal fluctuation. The variation of fluctuation field with the field verifies the effect of exchange coupling in Pr-Fe-B magnets, and the calculated value of fluctuation field is consistent with the aftereffect of thermal activation. With the increase of temperature the thermal fluctuation energy increases, and though the aftereffect of thermal fluctuation weakens due to the exchange coupling, the ratio of thermal fluctuation aftereffect to coercivity increases in Pr-Fe-B magnet.

关 键 词：热扰动 磁振子 磁畴壁 反磁化 

分 类 号：O469[理学—凝聚态物理]