Long range repulsive interactions in Fe on epitaxial graphene*

The understanding of metal nucleation on graphene is essential for promising future applications, especially of magnetic metals which can be used in spintronics. A common method to study the grown morphology is to measure the nucleated island density n as a function of growth parameters. Surprisingly the growth of Fe on graphene is found not to follow classical nucleation: n is unexpectedtly high, it increases continuously with the deposited amount $\theta $ and shows no temperature dependence. These unusual results indicate the presence of long range repulsive interactions. Kinetic Monte Carlo simulations and DFT calculations support this conclusion.