Strain-modulated ultrafast magneto-optic dynamics of graphene nanoflakes decorated with transition-metal atoms

We perform first-principles calculations and coherent laser-matter interaction analyses to investigate the laser-induced ultrafast spin flip on graphene nanoflakes(GNFs)with transition metal elements attached on the boundary[TM&GNFs(TM=Fe,Co,Ni)].It is shown that the spin-flip process on TM&GNFs is highly influenced by the involved element species and the position attached to the nanoflakes.Furthermore,taking Ni&GNF as an example,the first-principles tensile test predicts that the variation of the C-Ni bond length plays an important role in the spin density distribution,especially for the low-lying magnetic states,and can therefore dominate the spin-flip processes.The fastest spin-flip scenario is achieved within 80 fs in a Ni&GNF structure under 10%tensile strain along the C-Ni bond.The local deformation modulation of spin flip provides the precursory guidance for further study of ultrafast magnetization control in GNFs,which could lead to potential applications in future integrated straintronic devices.