Ou Xuedong, Wang Hongbo, Fan Fengren, Li Zhengwei, Wu Hua
Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China.
Science and Technology on Reliability and Environmental Engineering Laboratory, Beijing Institute of Spacecraft Environment Engineering, Beijing 100094, China.
Phys Rev Lett. 2015 Dec 18;115(25):257201. doi: 10.1103/PhysRevLett.115.257201. Epub 2015 Dec 17.
Large magnetic anisotropy energy (MAE) is desirable and critical for nanoscale magnetic devices. Here, using ligand-field level diagrams and density functional calculations, we well explain the very recent discovery [I. G. Rau et al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001) surface has a large MAE of more than 60 meV. More importantly, we predict that a giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and even more for the Os adatoms (208 meV). This is a joint effect of the special ligand field, orbital multiplet, and significant spin-orbit interaction, in the intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens. The giant MAE could provide a route to atomic scale memory.
大磁各向异性能量（MAE）对于纳米级磁性器件而言是理想且至关重要的。在此，利用配体场能级图和密度泛函计算，我们很好地解释了最近的一项发现[I. G. 劳等人，《科学》344, 988 (2014)]，即MgO(001)表面上单个Co吸附原子具有超过60 meV的大MAE。更重要的是，我们预测对于MgO(001)上的Ru吸附原子，可实现高达110 meV的巨大MAE，而对于Os吸附原子甚至更高（208 meV）。这是表面氧原子上方Ru或Os吸附原子处于中间自旋态时，特殊配体场、轨道多重态和显著自旋 - 轨道相互作用的共同效应。这种巨大的MAE可为原子尺度存储器提供一条途径。
