铁磁/反铁磁双层膜系统中交换各向异性及其厚度依赖性

Thickness Dependence of Positive Exchange Bias in Ferromagnetic/Antiferromagnetic Bilayers

研究铁磁/反铁磁双层膜系统中交换偏置场和矫顽场的冷却磁场依赖性.结果表明,随着冷却磁场的增加,交换偏置场由负值向正值转变.在转变点附近,矫顽场有一个特别的增强,并达到最大值.结果同相关实验一致.研究铁磁层和反铁磁层厚度对交换偏置场和矫顽场的影响.发现,正负交换偏置场和矫顽场随着铁磁层厚度的增大而减小,但随反铁磁层厚度的变化关系复杂.在正交换偏置场的情形,随反铁磁层厚度的增大,交换偏置场增强,矫顽场减弱;在负交换偏置场的情形,随反铁磁层厚度的增大,交换偏置场减弱,矫顽场增强.

Cooling field dependence of exchange anisotropy was investigated in ferromagnetic （FM）/antiferromagnetic（AFM） bilayers with antiferromagnetic interface coupling. It shows that the exchange bias HE can change from negative to positive with increasing cooling field Hcf and coercivity Hc acquires a maximum near crossover of HE. Especially, effect of FM and AFM thickness on exchange anisotropy is discussed in detail. Both negative （ or positive） HE and Hc always decrease with increasing of FM thickness tFM, which shows good agreement with experimental observation. It demonstrates interfacial nature of the exchange anisotropy. However, AFM thickness tAFM dependence of exchange anisotropy is relatively complex. In the case of positive HE , with increasing of tAFM , HE increases and Hc decreases. But, in the case of negative HE, HE decreases and Hc increases with increasing tabu.