Influence of Cr growth on exchange coupling in Fe/Cr/Fe(100).
Influence of Cr growth on exchange coupling in Fe/Cr/Fe(100).
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Cr 生长对 Fe/Cr/Fe(100) 中交换耦合的影响。
DOI：
10.1103/physrevb.49.14564
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Celotta
中科院分区：
文献类型：
--
作者：
Pierce;Stroscio;Unguris;Celotta
用扫描电子显微镜和偏振分析（SEMPA）测量了Fe/Cr/Fe（100）结构中交换耦合振荡对Cr生长温度的依赖性，并与用扫描隧道显微镜（STM）在相似生长温度下测量的Cr膜厚度波动相关联。用扫描隧道显微镜（STM）观察到，当沉积温度≥ 300 ℃时，Cr沉积在非常扁平的Fe（100）晶须上，形成了一层一层的生长。在此温度下，Fe覆盖层的磁化强度作为Cr间隔层厚度的函数的SEMPA测量可以通过周期为2.105±0.005d和12±1d的振荡耦合很好地模拟，其中d是层间距。受扩散动力学限制，较粗糙的Cr生长发生在较低的生长温度下，给出了由STM确定的生长前沿的厚度分布。我们模拟了较低温度的Cr生长的Fe磁化，假设在每个离散的Cr厚度的交换耦合是相同的，发现逐层生长。在每个平均Cr间隔层厚度处的总耦合通过将加权贡献加到来自对平均厚度有贡献的每个Cr层厚度的耦合来确定。因此，通过考虑到由STM确定的Cr间隔层中的厚度波动，在较低温度下Cr生长的Fe覆盖层磁化的模型和SEMPA测量之间获得了非常好的一致性，而不包括界面处的粗糙度的其他后果，例如平移不变性的破坏。重要的特征长度尺度和双二次耦合的SEMPA测量中的作用得到解决。
Scanning electron microscopy with polarization-analysis (SEMPA) measurements of the dependence of the oscillations of the exchange coupling in Fe/Cr/Fe (100) structures on the Cr growth temperature are correlated with the thickness fluctuations in Cr films measured by scanning tunneling microscopy (STM) at similar growth temperatures. Layer-by-layer growth was observed by STM for Cr deposition on very flat Fe (100) whiskers at deposition temperatures≥ 300 C. The SEMPA measurements of the magnetization of the Fe overlayer as a function of Cr spacer-layer thickness at this temperature could be simulated well by oscillatory coupling with periods 2.105±0.005d and 12±1d, where d is the layer spacing. Rougher Cr growth, limited by diffusion kinetics, occurs at lower growth temperatures giving a distribution of thicknesses in the growth front as determined by STM. We modeled the Fe magnetization for lower-temperature Cr growth by assuming that the exchange coupling at each discrete Cr thickness is the same as found for layer-by-layer growth. The total coupling at each average Cr spacer-layer thickness was determined by adding the weighted contribution to the coupling from each Cr layer thickness contributing to the average thickness. Thus, by taking into account the thickness fluctuations in the Cr spacer layer as determined by STM, very good agreement was obtained between the model and the SEMPA measurement of the Fe overlayer magnetization for Cr growth at lower temperatures without including other consequences of roughness at the interface, such as the breakdown of translational invariance. Important characteristic length scales and the role of biquadratic coupling in the SEMPA measurements are addressed.