Exchange and correlation effects on plasmon dispersions and Coulomb drag in low-density electron bilayers

Abstract

We investigate the effect of exchange and correlation ͑XC͒ on the plasmon spectrum and the Coulomb drag between spatially separated low-density two-dimensional electron layers. We adopt a different approach, which employs dynamic XC kernels in the calculation of the bilayer plasmon spectra and of the plasmon-mediated drag, and static many-body local field factors in the calculation of the particle-hole contribution to the drag. The spectrum of bilayer plasmons and the drag resistivity are calculated in a broad range of temperatures taking into account both intra-and interlayer correlation effects. We observe that both plasmon modes are strongly affected by XC corrections. After the inclusion of the complex dynamic XC kernels, a decrease of the electron density induces shifts of the plasmon branches in opposite directions. This is in stark contrast with the tendency observed within random phase approximation that both optical and acoustical plasmons move away from the boundary of the particle-hole continuum with a decrease in the electron density. We find that the introduction of XC corrections results in a significant enhancement of the transresistivity and qualitative changes in its temperature dependence. In particular, the large high-temperature plasmon peak that is present in the random phase approximation is found to disappear when the XC corrections are included. Our numerical results at low temperatures are in good agreement with the results of recent experiments by Kellogg et al. ͓Solid State Commun. 123, 515 ͑2002͔͒.

Coulomb drag

“…Drag or similar measurements of interlayer interactions were also considered for composite (or hybrid) systems comprising ballistic quantum wires Muradov, 2000, 2005;Raichev and Vasilopoulos, 2000a;Wang et al, 2005), coupled 2D-1D systems (Lyo, 2003), nonequilibrium charged gases (Wang and da Cunha Lima, 2001), multi-wall nanotubes (Lunde et al, 2005;Lunde and Jauho, 2004), quantum point contacts (Levchenko and Kamenev, 2008a), few level quantum dots (Moldoveanu and Tanatar, 2009), optical cavities (Berman et al, 2010a(Berman et al, , 2014, coupled mesoscopic rings (Yang and MacDonald, 2001), superconductors (Levchenko and Norman, 2011), and normalmetal-ferromagnet-normal-metal structures . Other developments include mesoscopic fluctuations of Coulomb drag (Narozhny and Aleiner, 2000;Narozhny et al, 2001), frictional drag mediated by virtual photons (Donarini et al, 2003) and plasmons (Badalyan et al, 2007), exciton effects in semiconductors (Laikhtman and Solomon, 2006) and topological insulators (Mink et al, 2012), interlayer Seebeck effect (Lung and Marinescu, 2011) and spin drag (Badalyan and Vignale, 2009;D'Amico and Vignale, 2000;Duine et al, 2011Duine et al, , 2010Duine and Stoof, 2009;Flensberg et al, 2001;Glazov et al, 2011;Pustilnik et al, 2006;Tse and Das Sarma, 2007;Vignale, 2005). Recently, the focus of the theoretical work was shifted towards the drag effect in graphene-based devices (Narozhny, 2007;Narozhny et al, 2015;Song et al, 2013; and strongly interacting high-mobility double...…”

Enhancement of Coulomb drag in double-layer graphene structures by plasmons and dielectric background inhomogeneity

“…For small values of k F d 1 (for the density n considered here we have k F d ∼ 1 for d ∼ 6) the typical momenta q in drag scattering events are of the order of q T = T /v and do not depend on d. In this case we find that the drag resistivity decreases as ρ D ∝ d −δ with δ 2. For larger separations with k F d 1 the drag mediated by the electron-hole fluctuations is dominated by the momenta q d −1 and we find that the drag resistivity calculated within the static screening approximation behaves approximately as d −4 [26,33]. At large separations the effect of the dielectric inhomogeneity on the spacing dependence of drag is weak (cf.…”

Spin Hall Drag in Electronic Bilayers

“…Because of the requirements of momentum and energy conservation in electron-electron scattering ρ CD vanishes as T 2 at low temperature T . A typical value in GaAs quantum wells is ρ CD ∼20 Ω at a temperature of a few Kelvin [6,7].Another effect of great current interest is the Spin Hall Effect [8]- [25], i.e. the generation of a transversal spin accumulation by an electric current in a single electron layer.…”

“…Because of the requirements of momentum and energy conservation in electron-electron scattering ρ CD vanishes as T 2 at low temperature T . A typical value in GaAs quantum wells is ρ CD ∼20 Ω at a temperature of a few Kelvin [6,7].…”