Phases of 4He and H2 adsorbed on doped graphene

The influence of attractive boron impurities, embedded on a graphene sheet, on the phase diagrams of ${}^4$He and H${}_2$ adsorbed on top was studied using the diffusion Monte Carlo method. The doping of graphene was made by distributing the boron atoms following the same pattern found in an experimentally synthesized substrate. Our results show that while the different incommensurate solid phases of both adsorbates remain largely unchanged after doping, the liquid/gas equations of state are significanty different from the ones on pristine graphene. Doping graphene produces new translationally invariant stable phases for ${}^4$He, depending on the concentration of boron impurities, but makes the H${}_2$ ground state to remain solid. In addition, several new registered phases appear for both adsorbates.