Electron decay rates in a zero-gap graphite layer

A 2D monolayer graphite exhibits rich Coulomb excitations and deexcitations, mainly owing to the zero-gap characteristic. The low-frequency electronic excitations include interband e-h excitations, intraband e-h excitations, and plasmon. The two latters are purely caused by temperature. The Coulomb decay rate strongly depends on temperature and wave vector (or energy), and the analytic formulas between them are absent. The Coulomb decay rate of the Fermi-momentum state only comes from the intraband e-h excitations. It grows quickly as temperature increases. Its value is close to the measured results of the layered graphite. As to other states, three kinds of electronic excitations make important contributions to the Coulomb decay rates and cause the novel dependence on wave vector. The Coulomb decay rate is much faster than the electron-phonon scattering rate. A 2D monolayer graphite quite differs from a 2D electron gas or a 1D gapless carbon nanotube in electronic excitations and deexcitations. (c) 2006 Elsevier B.V. All rights reserved.