We investigate the effect of edge defects (vacancies) and impurities (substitutional dopants) on the robustness of spin-polarization in graphene nanoribbons (GNRs) with zigzag edges, using density-functional-theory calculations. We found that the stability

Suppressionofspin-polarizationingraphenenanoribbonbyedge

defectandimpurity

BingHuang1,FengLiu2 ,JianWu1,Bing-LinGu1,andWenhuiDuan1

arXiv:0708.1795v2 [cond-mat.mtrl-sci] 21 Feb 20081DepartmentofPhysics,TsinghuaUniversity,Beijing100084,PRCand2DepartmentofMaterialsScienceandEngineering,UniversityofUtah,SaltLakeCity,Utah84112(Dated:February21,2008)AbstractWeinvestigatethee ectofedgedefects(vacancies)andimpurities(substitutionaldopants)ontherobustnessofspin-polarizationingraphenenanoribbons(GNRs)withzigzagedges,usingdensity-functional-theorycalculations.Thestabilityofthespinstateanditsmagneticmomentsisfoundtodecreasecontinuouslywithincreasingconcentrationofdefectsorimpurities.Thesystemgenerallybecomesnon-magneticattheconcentrationofoneedgedefect(impurity)per～10 A.ThespinsuppressionisshowntobecausedbyreductionandremovalofedgestatesattheFermienergy.OuranalysisimpliesanimportantcriterionontheGNRsamplesforspintronicsapplications.PACSnumbers:75.75.+a,73.22.-f,75.30.Hx