NiFe/Cu多层膜的结构与层间耦合效应

用直流磁控溅射方法在玻璃基片上制备了[Ni_(80)Fe_(20)/Cu]_(20)多层膜,其中采用了靶表磁场强度不同的靶腔沉积铜层,利用X射线衍射和振动样品磁强计对Cu(100nm)/[Ni_(80)Fe_(20)(0.9nm)/Cu(tCu)]_(20)两个系列样品的结构和磁性进行了表征。靶表磁场较弱时沉积的多层膜具有良好的层间耦合振荡行为,而靶表磁场较强时制备的多层膜没有出现反铁磁耦合。依据上述事实,我们推测靶表磁场强度的不同会影响Ni Fe/Cu界面扩散,进而对多层膜样品的磁性产生影响。用靶表磁场较弱的靶腔沉积中间层铜能够有效减小界面互溶程度,改善镍铁与铜的成层质量。而靶表磁场较强的靶腔溅射出的铜原子具有较高能量,在界面处扩散并与镍铁层互溶,破坏了层状结构。

Structure and interlayer exchange coupling in NiFe/Cu multilayers

The [Ni80Fe20/Cu]20 multilayers(MLs) were deposited on glass substrates by dc magnetron sputtering, in which copper layers were prepared by target chambers with different magnetic field intensities at surface. These two series of MLs are characterized by means of X-ray diffractometer and vibrating sample magnetometer. There are fine interlayer exchange coupling oscillations in the MLs deposited by the target chamber with weak magnetic field at surface. While the MLs prepared by the target chamber with strong magnetic field at surface exhibit no antiferromagnetic coupling. According to these facts, we speculate that different magnetic field intensities at the surface of target chamber will cause difference of interface diffusion in the MLs, thus having an influence on magnetic properties. Preparation of middle copper layers with the target chamber with weak magnetic field at surface can reduce the degree of interfacial miscibility effectively and improve the quality of NiFe and Cu layers. While the sputtered Cu atoms when using the target chamber with strong magnetic field have higher energy to diffuse and mix with NiFe layers, damaging the layered structure.