▎ 摘　　要

The magnetic properties based on the armchair-edged graphene nanoribbons (AGNRs) are less studied in currently existing works. Here, the edge modification of AGNR by the transition metal Mn (AGNR-Mn) and further functionalized with monohydrogenation (AGNR-Mn-H) and dihydrogenation (AGNR-Mn-H-2) are considered. Our calculations from first-principles method show that they posses three triplet anti-ferromagnetic (AFM) states, which are all semiconductoring for AGNR-Mn and metallic for AGNR-Mn-H-2, but semiconductoring or metallic for AGNR-Mn-H. Interestingly, at ferromagnetic (FM) state AGNR-Mn-H and AGNR-Mn-H-2 are a half-metal with bandgaps 0.46 and 0.97 eV, respectively. AGNR-Mn-H-2 featuring both the stable magnetic ordering and the highest energy stability are predicted, as well as the calculated Gibbs free energy unveils that these three structures can stably exist in a different chemical potential range in experiment. Also shown is that the perfect spin polarization in a very large bias region and a spin-valve effect with a large magnetoresistance can be achieved in a magnetic device based on AGNR-Mn-H-2. (C) 2016 Elsevier Ltd. All rights reserved.