Room Temperature Spin Transport in C$_{60}$-based spin valves.*

Carbon-based materials offer a unique playground for spin transport studies by merging relatively small spin relaxation mechanisms with the potential chemical versatility of some organic molecules. However, how the spin travels inside such materials is far from understood. In this work, we present magneto-transport studies in vertical spin valves containing a C$_{60}$ non-magnetic spacer and simple ferromagnetic (Co and Py) electrodes. Large magnetoresistance values (up to 5{\%}) are recorded at room temperature for fullerene thickness up to 30 nm. Remarkably, magnetoresistance is also present at relatively high bias (1 Volt), highlighting the robustness of the spin transport in this material. By choosing such a simple carbon system we are also able to introduce a simple multi-step tunneling model, which explain the electronic transport data and which is compatible with coherent spin transport over long distances.