Magnetic zigzag edges of graphene are considered as a basis for novel spintronics devices despite the fact that no true long-range magnetic order is possible in one dimension. We study the transverse and longitudinal fluctuations of magnetic moments at zigzag edges of graphene from first principles. We find a high value for the spin wave stiffness D=2100 meV angstrom(2) and a spin-collinear domain wall creation energy E-dw=114 meV accompanied by low magnetic anisotropy. Above the crossover temperature T-x approximate to 10 K, the spin correlation length xi proportional to T-1 limits the long-range magnetic order to similar to 1 nm at 300 K while below T-x, it grows exponentially with decreasing temperature. We discuss possible ways of increasing the range of magnetic order and effects of edge roughness on it.
Bruce Normand, Ying Chen, Sheng Xu, Shuo Li, Xiaoyu Xu, Zeyu Wang, Weiqiang Yu
Ellen Fogh, Sofie Janas, Paola Caterina Forino