Concurrence of strong spin-orbit and exchange interactions in graphene

• Applicant: Professor Dr. Oliver Rader
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2010 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 173709208

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.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1459: Graphen