Title: The theoretical study of the correlation between band filling and Coulomb interaction in the charge gap of graphene-on-substrate in paramagnetic limit
Authors: Rudrashish Panda; Sivabrata Sahu; G.C. Rout
Addresses: Department of Physics, School of Applied Sciences, KIIT University, Campus-3, 751024, Odisha, India ' School of Basic Sciences, Indian Institute of Technology Bhubaneswar, 751050, Odisha, India ' P.G. Department of Applied Physics and Ballistics, Fakir Mohan University, Vyasa Vihar, Balasore, India
Abstract: A suitable substrate breaks the sub-lattice symmetry leading to generation of a gap at the Fermi level. We propose here a tight binding model Hamiltonian for graphene on a substrate with nearest neighbour-hopping in presence of symmetry breaking interaction due to substrate effect. The sub-lattice Coulomb interaction between the electrons which produces varieties of magnetic, non-magnetic and collective interactions is considered within mean-field approximation in the paramagnetic limit. The Hamiltonian is solved by Zubarev's double time Green's function technique. The electron occupancies of the two sub-lattices are calculated from the correlation functions. Finally, the expression for the temperature dependent charge gap is derived and calculated numerically. The evolution of the charge gap in graphene is investigated by varying the Coulomb interaction, electron-occupancy and substrate induced gap. The magnitude of the electron occupancy at A-site becomes larger than that at B-site indicating symmetry breaking of the two sub-lattices of graphene.
Keywords: grapheme; paramagnetism; Coulomb interaction; charge gap.
International Journal of Nano and Biomaterials, 2019 Vol.8 No.1, pp.54 - 63
Accepted: 12 May 2018
Published online: 30 Jan 2019 *