▎ 摘　　要

The properties in magnetic ordered states of graphene nanoribbons with zigzag-shaped edges are investigated by applying mean-field approximation to the Hubbard model with the on-site repulsion U. We observe that magnetic moments and critical temperature show anomalous power-law dependences as a function of U; the actual values of the power are determined by only the width of the ribbons. Such singular behaviours are found to be due to the localized nature of the electronic states close to the Fermi energy.