Graphene-based systems for spintronics: Magnetic interactions at the graphene/3d metal interface SpinGraph

石墨烯与金属，特别是铁磁性材料相互作用的特殊性质是本提案研究活动的中心。石墨烯中长的电子平均自由程和可忽略的自旋-轨道耦合导致了较大的自旋弛豫时间，使石墨烯成为弹道自旋输运的理想材料。与磁性衬底的相互作用使石墨烯-铁磁界面成为实现自旋场效应晶体管(Spin FET)的可行系统，该系统仅通过施加电场来操纵注入电子的自旋。近年来，自旋滤光器和自旋场效应管的应用一直是许多理论研究的焦点，但目前几乎没有实验工作。这些输运性质受到特定原子环境的强烈影响，这些效应需要详细研究。理论预测表明，石墨烯本身虽然不具有磁性，但作为一种延伸的“2D固体”，实际上可能在结构和化学缺陷处获得磁矩，即在所谓的纳米带边缘，或者在带有缺陷位(如氢)的石墨烯中，但没有实验验证。最后，在更实用的情况下，石墨烯可以提供一种理想的手段来化学钝化磁性层，或者提供用于创建磁性纳米团簇有序阵列的“纳米网格”模板，这可能对高密度数据存储感兴趣。为了在(I)惰性自旋过滤装置和自旋阀以及(Ii)高密度磁存储装置的背景下促进对石墨烯/3D-金属系统的理解，工作计划被分成两个相互关联的主要主题。它们还涉及对石墨烯基本物理性质的持续研究，主要研究重点转向研究石墨烯/3D-金属混合体系的电子和磁性。

The specific properties of graphene in its interaction with metallic, and in particular ferromagnetic, materials are at the centre of research activities of the present proposal. The long electronic mean free path and negligible spin-orbit coupling in graphene lead to large spin relaxation times and make graphene an ideal material for ballistic spin transport. The interaction with magnetic substrates thus makes the graphene-ferromagnet interface a viable system for the realization of spin field-effect transistors (spin FET), based on the manipulation of the spin of an injected electron solely via the application of an electric field. Such applications as spin filters and spin FETs have been recently at the focus of many theoretical investigations, but almost no experimental work exists at present. These transport properties are strongly influenced by the specific atomic environment, effects which need to be studied in detail. Theoretical predictions indicate that graphene itself, while nonmagnetic as an extended “2D solid”, may actually acquire a magnetic moment at structural and chemical defects, namely at the edge of so-called nanoribbons, or in graphene decorated with defect sites, such as hydrogen, but no experimental verification exists. Finally, graphene may provide, in a more applied context, an ideal means to chemically passivate magnetic layers, or to provide a “nanomesh” template for the creation of ordered arrays of magnetic nanoclusters, of possible interest for high density data storage. In order to contribute to an understanding of graphene/3d-metal systems in the context of (i) inert spin-filtering devices and spin valves, and (ii) high-density magnetic storage devices, the work program is split into two strongly interlinked main topics. They also involve a continuation of ongoing research on the fundamental physical properties of graphene, with the main research focus shifting towards the investigation of the electronic and magnetic properties of hybrid graphene/3d-metal systems.