用角分辨光电子能谱研究Co/Cu(111)外延超薄膜的电子结构  

Study of Electronic Structure of Ultrathin Co Films Epitaxially Grown on Cu (111) by Angle-Resolved Photoemission Spectroscopy

作　　者：苏润[1] 刘凤琴[1] 钱海杰[1] 

机构地区：[1]中国科学院高能物理研究所,北京100039

出　　处：《高能物理与核物理》2003年第2期178-182,共5页High Energy Physics and Nuclear Physics

摘　　要：利用同步辐射角分辨光电子能谱研究了分子束外延生长的Co Cu( 111)超薄膜电子结构的变化 .Cu( 111)的位于表面布里渊区Γ点的表面态在覆盖度为两单层时仍然可以分辨 ,说明薄膜生长模式不是二维层状生长 .在一单层和二单层时 ,动量沿Cu体布里渊区Γ Λ L方向变化 ,Co的最明显的峰包有能量色散 .在覆盖度从一单层到两单层的变化过程中 ,固定光子能量测谱发现Co的能带的能量调整 .实验测得的Co膜的电子结构与已有理论计算的结果对比 ,初步确定Co原子在生长初期阶段为两层岛生长 ,而且在一单层时已经具有铁磁性 .Electronic structure of Co films grown by molecular-beam epitaxy on Cu (111) surface was studied by Synchrotron Radiation angle-resolved Photoemission Spectroscopy. The peak intensity of the surface state at the Γ point of Cu(111) surface Brillouin zone still can be distinguished even at the coverage of 2ML, which means that the growth mode is not the two-dimensional layer-by-layer mode. With changing the momentum along the direction of Γ-Λ-L of Brillouin zone of bulk copper by varying photon energy, we find that the most prominent peak of cobalt film both at the coverage of 1ML and 2ML disperses like that of the surface of Co(0001). With a fixed photon energy for the coverage of cobalt from 1ML to 2ML, the changes of cobalt energy band were obtained. It shows that the 3d-band modification do exist because of the interaction of substrate and film atoms at the initial stage of growth. Compared with theoretical calculations, we find that films show ferromagnetic characters even at 1ML thickness, and they might grow as bilayer island at the initial period of growth.

关 键 词：Co/Cu(111) 外延超薄膜 角分辨光电子能谱 电子结构 交换劈裂 铁磁性 分子束外延生长 铜衬底 钴原子 

分 类 号：O484.1[理学—固体物理] O484.5[理学—物理]