▎ 摘　　要

Assembly of interacting molecular spins is an attractive candidate for spintronic and quantum computing devices. Here, we report on-surface chemical assembly of aminoferrocene molecules on a graphene oxide (GO) sheet and their magnetic properties. On the GO surface, organometallic molecules having individual spins through charge transfer between the molecule and the sheet are arranged in nanoclusters having diameters of about 2 nm. The synthetic fine tuning of the reaction time enables to change the interspacing between the nanoclusters, keeping their size intact. Their magnetism changes from paramagnetic behavior to collective one gradually as the interspacing decreases. The creation of collective nature among weakly interacting molecular spins through their nanoscale arrangement on the GO surface opens a new avenue to molecular magnetism.