Neutral triplet collective mode as a decay channel in graphite

作者：Ebrahimkhas M^*; Jafari S A

来源：Physical Review B, 2009, 79(20): 205425.

DOI：10.1103/PhysRevB.79.205425

• bosons
• Brillouin zones
• graphene
• graphite
• polarons
• tight-binding calculations

In an earlier work we predicted the existence of a neutral triplet collective mode in undoped graphene and graphite [G. Baskaran and S. A. Jafari, Phys. Rev. Lett. 89, 016402 (2002)]. In this work we study a phenomenological Hamiltonian describing the interaction of tight-binding electrons on honeycomb lattice with such a dispersive neutral triplet boson. Our Hamiltonian is a generalization of the Holstein polaron problem to the case of triplet bosons with nontrivial dispersion all over the Brillouin zone. This collective mode constitutes an important excitation branch which can contribute to the decay rate of the electronic excitations. The presence of such collective mode modifies the spectral properties of electrons in graphite and undoped graphene. In particular such collective mode, as will be shown in this paper, can account for some parts of the missing decay rate in a time-domain measurement of the excitation lifetime in graphite.

• 出版日期2009-5