成分和厚度的依赖

通过调整Mn的成分，系统地研究了Ni81Fe19/Ni100-xMnx双层膜的磁学性质，特别是交换偏置场(Hex)的变化.当Ni100-xMnx中Mn的原子百分比在534%到600%之间时，对于150nm的Ni81Fe19，得到了最大的交换偏置场175kA/m，同时由于Mn对Ni81Fe19层的扩散所造成的磁矩的降低小于20%；高角x射线衍射证明Ni100-xMnx的晶格常数随着Mn成分的改变而变化，Mn含量越多，其晶格常数越大；制备态Ni100-xMnx膜晶格常数与θ相NiMn膜晶格常数的接近程度与NiMn膜θ相形成的容易程度相对应.也研究了交换偏置场随着Ni１００-xMnx厚度的变化，第一次得到了当Ni100-xMnx中Mn的原子百分比为706%时，Ni81Fe19(150nm)/Ni100-xMnx(90nm)双层膜在经过240℃，5h退火后，可以有80kA/m的交换偏置场，此时铁磁层磁矩的大小几乎不变. 关键词： Ni81Fe19/Ni100-xMnx 交换偏置场

The dependence of exchange bias of Ni81Fe19/Ni100-xMnx bilayers on the Mn content and the thickness of Ni100-xMnx

By adjusting the Mn concentration,we systematically investigated the magnetic properties,especially the exchange bias field(Hex),in Ni81Fe19/Ni100-xMnx bilayers.In the range of 534≤x≤600,the largest exchange bias field(～175kA/m)was achieved,and at the same time the reduction of magnetic moment due to the Mn diffusion into the Ni81Fe19 layer was lower than 20%.High-angle x-ray diffraction(XRD)showed a variation of Ni１００-xMnx lattice parameters when altering the Mn content:the more the Mn content,the larger the lattice parameters.It was found that the as-deposited Ni100-xMnx films with their lattice parameters close to those of θ-phase of NiMn alloy could be transformed into θ-phase relatively easily.Finally, the exchange bias of the bilayers with different Ni100-xMnx thicknesses was studied.We first obtain a 80 kA/m exchange bias field in the Ni81Fe19(150nm)/Ni100-xMnx(90nm)bilayers when Mn content increases to 706% after annealed at 240℃ for 5h,while the magnetic moment of the ferromagnetic layer was nearly umchanged.