铁磁/反铁磁双层膜系统中的交换偏置及矫顽场的温度特性(英文)  

TEMPERATURE DEPENDENCE OF EXCHANGE BIAS AND COERCIVITY IN FERROMAGNETIC AND ANTIFERROMAGNETIC BILAYERS

作　　者：胡经国[1] 金国钧[2] 马余强[2] 

机构地区：[1]扬州大学物理科学与技术学院,扬州225002 [2]南京大学固体微结构实验室,南京210093

出　　处：《低温物理学报》2003年第2期88-95,共8页Low Temperature Physical Letters

基　　金：江苏省自然科学基金 (No .0 1KJD140 0 0 8)~~

摘　　要：提出了一个讨论铁磁 /反铁磁双层膜中的交换偏置及矫顽场温度特性的物理模型 ,该模型 ,假设铁磁层为具有单轴各向异性的单畴膜而反铁磁层由许多相互独立具有多晶各向异性的颗粒组成 ,其温度依赖性主要来源于系统态的热不稳定 ,包括反铁磁颗粒易轴取向的热涨落和相关磁学量的温度依赖性等 .计算结果表明其交换偏置随温度的增加非线性地减少而其矫顽场在体阻截温度处达极大值 ,且其体阻截温度随反铁磁颗粒粒径的增加而增加 .我们的计算结果和相关实验结果一致 .通过本文的讨论 ,我们建议通过铁磁膜耦合上大粒径硬反铁磁颗粒膜可获得高交换偏置。A available model is presented for the temperature dependence of exchange bias and coercivity in ferromagnetic (FM) and antiferromagnetic (AFM) bilayers. In this model, the FM layer is considered as a single domain with uniaxial anisotropy while the AFM layer is treated as many independent AFM grains with polystalline anisotropy. The temperature dependence comes from the thermal instability of the system state, including the thermal fluctuation of orientations of easy axes of AFM grains and the temperature modulated relative magnetic parameters. These results show that, the exchange bias nonlinearly decreases with increasing temperature but there is a peak for the coercivity. The block temperature increases with size increase of AFM grains. These results are in good agreement with experimental results qualitatively. Based on our discussion, we can conclude that FM layer coupled by a hard AFM layer comprised by large size of AFM grain may be very applicable to design magnetic devices almost independent of temperature with high exchange bias and low coercivity.

关 键 词：铁磁/反铁磁双层膜系统 交换偏置 矫顽场 温度特性 物理模型 交换耦合 温度信赖性 

分 类 号：O484.43[理学—固体物理]