x射线磁性圆二色吸收谱分析Co膜厚度对原子磁矩和自旋磁矩的影响

Research on the effects of thickness of cobalt layers on the orbital and spin moments of Co atoms using x-ray magnetic circular dichroism in absorption

利用软x射线磁性圆二色吸收谱(XMCD)研究了Si衬底上沉积的不同厚度的Co膜的轨道磁矩和自旋磁矩.样品是磁控溅射方法制备的,膜的厚度分别是2nm,10nm和30nm,并在表面覆盖0.8—1nm厚的金膜防止样品的氧化.根据XMCD求和定则计算得到的轨道磁矩和自旋磁矩分别是0.249—0.195μB(玻尔磁子)和1.230—1.734μB.随着膜厚的减小,Co原子的轨道磁矩增加,而自旋磁矩下降.轨道磁矩与总磁矩的比值由0.101上升至0.168,即2nm膜中Co原子的轨道磁矩对总磁矩的贡献比30nm膜中Co原子的大了83%.

Orbital and spin moments of Co atoms in films of different thickness deposited by magnetron-sputtering on silicon wafers have been investigated by use of soft x-ray magnetic circular dichroism in absorption. Layers with thickness 2nm, 10nm and 30nm are covered by 0.8-1nm of protection overlayer. Orbital and spin moments of 0.249-0.195μB and 1.230-1.734μB are found from XMCD sum rules. Increase in orbital moments and decrease in spin moments are observed with reducing cobalt film thickness. There is a ratio variation from 0.101 to 0.168 of orbital moment to total moment, that is, contribution of orbital moment of cobalt atoms to total moment in 2nm film is 83% greater than that in the 30nm film.