磁性多层膜层间交换耦合的自由电子模型研究

基于自由电子模型,考虑到不同膜厚和不同磁化排列的费密能的不同,自洽地给出费密能。利用这种方法,计算了材料铁磁层和非磁层电子密度对层间耦合振荡周期的影响,并比较了我们所得结果与他人按巨势法得到的结果的异同,发现振荡周期随着电子密度的变化而改变,并且当铁磁层和非磁层的电子密度不同时,将出现不等周期的振荡。这一新的理论结果与最近的实验相符。此外,还计算了极化强度和由于能带不匹配造成的接触势对耦合强度及振荡相位的影响:前者是决定耦合强度的主要因素,后者则会影响振荡相位,甚至周期。 关键词：

FREE ELECTRON MODEL STUDY ON INTERLAYER EXCHANGE COUPLING IN MAGNETIC MULTILAYERS

Based on the free electron model, a self-consistent approach is adopted to calculate the Fermi energy and its variation with the layer thickness and the magnetlization alignment in magnetic multilayers . Then we study the effect of the thickness of magnetic and non-magnetic layers, especially of electron density on the oscillation period of interlayer exchange coupling in such multilayer. A comparison of our theoretical results with those obtained by using the grand potential method is made, we find that the oscillation period is strongly dependent on the electron density. When the electron density in magnetic layer is different from that in spacer, the period will change as changing the thickness ratio of spacer to magnetic layer. This new result agree with the latest experimental data. In addition, our calculation also shows that the coupling strength is mainly determined by the polarization force experienced by electrons, while the band mismatch does influence the phase and even the period of the coupling oscillation.