Effect of vacancy defects on electronic band structure and magnetic moment of single-layered graphene: A density functional theory study

In the present work, the density functional theory is used to study the electronic band structure and magnetic moment of single-layered pristine graphene and graphene with vacancy defects. The 4x4x1 supercell graphene consisting of 32 C atoms is used as pristine graphene (PG) and made the structure with a single vacancy (1V) and double vacancies (2V). The results show that the Dirac cone that exists in pristine graphene disappears in the graphene with vacancies. The DOS of spin up and down electrons in graphene with vacancies shows a mismatch, which is due to unpaired electrons. Vacancy defects also cause the presence of states at the Fermi level, which are not found in pristine graphene. Then, the double vacancies have a higher magnetic moment value than the single vacancy.