▎ 摘　　要

Thanks to its outstanding electronic properties, like very high mobility of carriers, graphene has emerged in recent years as exciting candidate for use in new electronic devices When it is patterned in the form of ribbons with widths in the range of nanometers, its transport properties become strongly influenced by the presence of the states localized at the edges of the ribbon Using first principles calculations we study the properties of these states for both isolated ribbons and in the presence of metallic electrodes The calculations were performed for end contacted geometry i e for graphene sheets at right angle to the electrodes Both para- and ferromagnetic electrodes were considered