Suchergebnisse

The way conduction electrons respond to ultrafast external perturbations in low dimensional materials is at the core of the design of future devices for (opto)electronics, photodetection and spintronics. Highly charged ions provide a tool for probing the electronic response of solids to extremely strong electric fields localized down to nanometre-sized areas. With ion transmission times in the order of femtoseconds, we can directly probe the local electronic dynamics of an ultrathin foil on this timescale. Here we report on the ability of freestanding single layer graphene to provide tens of electrons for charge neutralization of a slow highly charged ion within a few femtoseconds. With values higher than 1012 A cm−2, the resulting local current density in graphene exceeds previously measured breakdown currents by three orders of magnitude. Surprisingly, the passing ion does not tear nanometre-sized holes into the single layer graphene. We use time-dependent density functional theory to gain insight into the multielectron dynamics. ; We acknowledge funding by Austrian Science Fund (FWF): project number: I1114-N20 and the German DFG (project number:WI 4691/1-1). We also acknowledge partial financial support from Gobierno Vasco project number IT-756-13 and MINECO project number FIS2013-48286-C2-1-P. We further acknowledge funding and fruitful discussions within the SPP 1495 'Graphene' and the collaborative research centre SFB 1242 'Non-equilibrium dynamics in condensed matter in the time domain' funded by the DFG. B.C.B. acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 656214-2DInterFOX. We are grateful for discussions with C. Lemell, J. Burgdörfer, P. Tiwald and I. Floss. We thank M. Heidelmann from the Interdisciplinary Center for Analytics on the Nanoscale (ICAN, core facility funded by the German Research Foundation, DFG) for support with the TEM Measurements. ; Peer reviewed