Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects ha...Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects have been widely studied,collective magnetic behaviors originating from well-organized multiple topological defects remain a great challenge.Here,we examined the collective magnetic properties originating from three pentagon topological defects in truxene-based molecular graphenoids using scanning tunneling microscopy(STM)and non-contact atomic force microscopy.Unpairedπelectrons were introduced into the aromatic topology of truxene molecular graphenoids one by one by dissociating hydrogen atoms at the pentagon defects via atom manipulation.STM measurements,together with density functional theory calculations,suggested that the unpaired electrons were ferromagnetically coupled,forming a collective highspin quartet state of S=3/2.Our work demonstrates that collective spin ordering could be realized through engineering regular patterned topological defects in molecular graphenoids,providing a new platform for designing one-dimensional ferromagnetic spin chains and two-dimensional ferromagnetic networks.展开更多
基金S.W.acknowledges the financial support from the National Key R&D Program of China(grant no.2020YFA0309000)the National Natural Science Foundation of China(grant nos.11874258 and 12074247)+5 种基金the Shanghai Municipal Science and Technology Qi Ming Xing Project(grant no.20QA1405100)Fok Ying Tung Foundation for young researchers and SJTU(grant no.21X010200846)This work is also supported by the Ministry of Science and Technology of China(grant nos.2019YFA0308600,2016YFA0301003,and 2016YFA0300403)NSFC(grants nos.21925201,11521404,11634009,92065201,11874256,11790313,and 11861161003)the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB28000000)the Science and Technology Commission of Shanghai Municipality(grants nos.20ZR1414200,2019SHZDZX01,19JC1412701,and 20QA1405100)for partial support.
文摘Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects have been widely studied,collective magnetic behaviors originating from well-organized multiple topological defects remain a great challenge.Here,we examined the collective magnetic properties originating from three pentagon topological defects in truxene-based molecular graphenoids using scanning tunneling microscopy(STM)and non-contact atomic force microscopy.Unpairedπelectrons were introduced into the aromatic topology of truxene molecular graphenoids one by one by dissociating hydrogen atoms at the pentagon defects via atom manipulation.STM measurements,together with density functional theory calculations,suggested that the unpaired electrons were ferromagnetically coupled,forming a collective highspin quartet state of S=3/2.Our work demonstrates that collective spin ordering could be realized through engineering regular patterned topological defects in molecular graphenoids,providing a new platform for designing one-dimensional ferromagnetic spin chains and two-dimensional ferromagnetic networks.
