Novel behaviors of monolayer quantum gases on Graphene, Graphane and Fluorographene

Abstract

This article discusses the behavior of submonolayer quantum films (He and H2) on graphene and newly discovered surfaces that are derived from graphene. Among these substrates are graphane (abbreviated GH), which has an H atom bonded to each C atom, and fluorographene (GF). For the graphite case, extensive experimental and theoretical investigations have revealed that the phase diagrams of the bose gases 4He and para-H2 are qualitatively similar, differing primarily in a higher characteristic temperature scale for H2 than for He. The phase behaviors of these films on one side of pristine graphene, or both sides of free-standing graphene, are expected to be similar to those on graphite. We point out the possibility of novel phenomena in adsorption on graphene related to the large flexibility of the graphene sheet, to the non--negligible interaction between atoms adsorbed on opposite sides of the sheet and to the perturbation effect of the adsorbed layer on the Dirac electrons. In contrast, the behaviors predicted on GF and GH surfaces are very different from those on graphite, a result of the different corrugation, i.e., the lateral variation of the potential experienced by these gases. As a result of this novel geometry and potential, distinct properties are observed. For example, the 4He film's ground-state on graphite is a two-dimensional (2D) crystal commensurate with the substrate; on GF and GH, instead, it is predicted to be an anisotropic superfluid. On GF the anisotropy is so extreme that the roton excitations are very anisotropic, as if the bosons are moving in a multiconnected space along the bonds of a honeycomb lattice. Such a novel phase has not been predicted or observed previously on any substrate. Also, in the case of 3He the film's ground-state is a fluid, thus offering the possibility of studying an anisotropic Fermi fluid with a tunable density.

32 pages, 18 figures, accepted for publication in Journal of Physics: Condensed Matter as a topical review

References in corpus (12)

• The structure of suspended graphene sheets
• Control of graphene's properties by reversible hydrogenation
• Graphane: a two-dimensional hydrocarbon
• Fluorographene: Two Dimensional Counterpart of Teflon
• Domain Wall QCD with Near-Physical Pions
• Phase diagram of 4He adsorbed on graphite
• 4He on a single graphene sheet
• Population size bias in Diffusion Monte Carlo
• Phase diagram of ${}^4$He on graphene
• Observation of Self-binding in Monolayer ${}^3$He
• Excitation spectrum in two-dimensional superfluid 4He
• Preliminary Heat Capacity and Vapor Pressure Measurements of 2D 4He on ZYX Graphite

Cited by in corpus (7)

• Fermion-induced quantum critical points in two-dimensional Dirac semimetals
• Statistical and computational intelligence approach to analytic continuation in Quantum Monte Carlo
• Two-Dimensional Bose-Hubbard Model for Helium on Graphene
• A Perspective on Collective Properties of Atoms on 2D Materials
• Localization versus inhomogeneous superfluidity: Submonolayer He-4 on fluorographene, hexagonal boron nitride, and graphene
• Prediction for two spatially modulated superfluids: ${}^4$He on fluorographene and on hexagonal BN
• Effects of substrate corrugation during helium adsorption on graphene in the grand canonical ensemble