Concurrence of strong spin-orbit and exchange interactions in graphene

石墨烯中强自旋轨道和交换相互作用的同时存在

• 批准号: 173709208
• 负责人: Professor Dr. Oliver Rader
• 金额: --
• 依托单位: Gemeinsame Forschungsgruppe Kombinierte Röntgenmethoden im BLiX und BESSY II - SyncLab
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/173709208?language=en
• 关键词: Concurrence; strong; spin; orbit; exchange

Graphene is neither heavy nor magnetic and, therefore does not give rise to largespin-orbit interactions or exchange interactions. In the first funding period we have found the conditions for creating a giant (100 meV) Rashba-type spin orbit splitting in graphene, i. e., by interfacing it with Au or Ir. We have also found the conditions for creating highly spin-polarized Dirac fermions at the interface with Co (as well as Fe and Ni). In both cases the Dirac point remains intact an no band gap opens there. In the present second funding period we plan to combine these two effects and have two main aims: The first one (work package 1) is a Rashba+exchange effect in which the Rashba shift in k//-space can be controlled by the magnetization of the sample. This effect has previously been observed for a Gd(0001) surface state. We suggest two different approaches, i. e., intercalation and CVD growth on an alloy for its realization. In work package 2, we also use the simultaneous presence of spin-orbit and exchange interaction but with the aim to open the band gap at the Dirac point in the graphene by the spin-orbit interaction which is not possible by a Rashba effect. There are various predictions in the literature for the quantum spin Hall effect as well as the quantum anomalous Hall effect, and the systems we have been studying are close to fulfilling these predictions. Finally, in work package 3, we search for the strongly enhanced Kondo temperature of magnetic adatoms on graphene which has recently been predicted for the condition that graphene is subjected to Rashba spin-orbit coupling.

石墨烯既不重也没有磁性，因此不会产生大的自旋轨道相互作用或交换相互作用。在第一个资助期，我们已经找到了在石墨烯中产生巨大（100 meV） rashba型自旋轨道分裂的条件，即通过将其与Au或Ir相连接。我们还发现了在Co（以及Fe和Ni）界面上产生高度自旋极化的狄拉克费米子的条件。在这两种情况下，狄拉克点保持完整，没有带隙打开。在目前的第二个资助期，我们计划将这两种效应结合起来，并有两个主要目标：第一个（工作包1）是Rashba+交换效应，其中Rashba在k//-空间中的位移可以通过样品的磁化来控制。这种效应以前已经在Gd（0001）表面状态中被观察到。我们提出了两种不同的方法，即插层法和CVD生长法。在工作包2中，我们也同时使用了自旋轨道相互作用和交换相互作用，但目的是通过自旋轨道相互作用打开石墨烯中狄拉克点的带隙，这是Rashba效应无法实现的。文献中对量子自旋霍尔效应和量子反常霍尔效应有各种各样的预测，我们所研究的系统都接近于实现这些预测。最后，在工作包3中，我们寻找了石墨烯上磁性附着原子的强增强近藤温度，这是最近预测的石墨烯遭受Rashba自旋轨道耦合的条件。