3He on preplated graphite
arXiv:1610.06045 · doi:10.1103/PhysRevB.94.165421
Abstract
By using the diffusion Monte Carlo method, we obtained the full phase diagram of He on top of graphite preplated with a solid layer of He. All the He atoms of the substrate were explicitly considered and allowed to move during the simulation. We found that the ground state is a liquid of density 0.007 0.001 Å, in good agreement with available experimental data. This is significantly different from the case of He on clean graphite, in which both theory and experiment agree on the existence of a gas-liquid transition at low densities. Upon an increase in He density, we predict a first-order phase transition between a dense liquid and a registered 7/12 phase, the 4/7 phase being found metastable in our calculations. At larger second-layer densities, a final transition is produced to an incommensurate triangular phase.