We investigate the band structures of strained monolayer and bilayer graphene superlattice,which is formed by subjecting graphene to a periodic uniaxial strain.The strain superlattice is attained by imposing distincti...We investigate the band structures of strained monolayer and bilayer graphene superlattice,which is formed by subjecting graphene to a periodic uniaxial strain.The strain superlattice is attained by imposing distinctively positive and negative strains on opposite halves of the supercell.A controllable band gap and partial flat band are observed in superlattice,with the strain applied along the zigzag and armchair direction respectively.The band gap can be achieved with a small strain applied,and the magnitude of band gap can be tuned by adjusting the strength and smoothness of the strain,with maximal band gaps reaching 1200 meV and 900 meV for monolayer and bilayer graphene,respectively.The partial flat band can be used in inducing quantum valley Hall interface state(QVHIS)localized at the strain interface of bilayer strain superlattice,with a vertical electric field applied simultaneously.Our results provide a strategy for creating controllable band gap or QVHIS in graphene,which could be useful in designing graphene-based electronic devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12174077)the Bureau of Education of Guangzhou Municipality(Grant No.202255464)+1 种基金the Joint Fund with Guangzhou Municipality(Grant No.202201020238)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515110011).
文摘We investigate the band structures of strained monolayer and bilayer graphene superlattice,which is formed by subjecting graphene to a periodic uniaxial strain.The strain superlattice is attained by imposing distinctively positive and negative strains on opposite halves of the supercell.A controllable band gap and partial flat band are observed in superlattice,with the strain applied along the zigzag and armchair direction respectively.The band gap can be achieved with a small strain applied,and the magnitude of band gap can be tuned by adjusting the strength and smoothness of the strain,with maximal band gaps reaching 1200 meV and 900 meV for monolayer and bilayer graphene,respectively.The partial flat band can be used in inducing quantum valley Hall interface state(QVHIS)localized at the strain interface of bilayer strain superlattice,with a vertical electric field applied simultaneously.Our results provide a strategy for creating controllable band gap or QVHIS in graphene,which could be useful in designing graphene-based electronic devices.
