▎ 摘　　要

We present transport measurements on long, diffusive, graphene-based Josephson junctions. Several junctions are made on a single-domain crystal of CVD graphene and feature the same contact width of similar to 9 mu m but vary in length from 400 to 1000 nm. As the carrier density is tuned with the gate voltage, the critical current in these junctions ranges from a few nanoamperes up to more than 5 mu A, while the Thouless energy, E-Th, covers almost 2 orders of magnitude. Over much of this range, the product of the critical current and the normal resistance ICRN is found to scale linearly with E-Th, as expected from theory. However, the value of the ratio ICRN/E-Th is found to be 0.1-0.2, which much smaller than the predicted similar to 10 for long diffusive SNS junctions.