Quasiparticle renormalization inABCgraphene trilayers

Abstract

We investigate the effect of electron-electron interactions in ABC stacked graphene trilayers. In the gapless regime, we show that the self-energy corrections lead to the renormalization of the of dynamical exponent z = 3 + α1/N , with α1 ≈ 0.52 and N is the number of fermionic species. Although the quasiparticle residue is suppressed near the neutrality point, the lifetime has a sublinear scaling with the energy and the quasiparticles are well defined even at zero energy. We calculate the renormalization of a variety of physical observables, which can be directly measured in experiments. Introduction. In graphene single layers, the honeycomb arrangement of the carbon atoms leads to a linear electronic dispersion and to quasiparticles that behave as massless Dirac fermions, akin to massless neutrinos in quantum electrodynamics (QED) [1,2]. In graphene multilayers, the electronic spectrum varies depending on the stacking sequence. In the single particle picture, rombohedral ABC-stacked trilayer graphene reveals a gapless band structure of chiral quasiparticles with Berry phase 3π and cubic low energy excitation spectrum [3,4]. Because of the scaling of the kinetic energy, Coulomb interactions are relevant operators in the renormalization group (RG) sense, and can strongly renormalize different physical quantities. Different spontaneous broken symmetry ground states have been already proposed for trilayer graphene [5][6][7]. Very recently, transport experiments revealed a robust many-body gap of ∼40 meV at temperatures below T c ∼ 34K [8].In this letter we study the effect of Coulomb interactions and polarization effects on the behavior of the quasiparticles at small but finite temperature, when the many-body gap is zero. We investigate the analytical structure of the polarization bubble and the leading selfenergy corrections due to dynamically screened Coulomb interactions. In the gapless regime, we show that the dynamical critical exponent is renormalized to