Superfluid state of 4He on graphane and graphene-fluoride

Anisotropic roton states

M. Nava, D. E. Galli, Milton Walter Cole, L. Reatto

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We explore the phase behavior of Helium films on two variants of graphene: graphane (graphene coated with H, denoted GH) and graphene-fluoride (GF). A semiempirical interaction with these substrates is used in T=0 K Path Integral Ground State and finite temperature Path Integral Monte Carlo simulations. We predict that 4He forms anisotropic fluid states at low coverage. This behavior differs qualitatively from that on graphite because of the different surface composition, symmetry and spacing of the adsorption sites. The 4He ground state on both substrates is thus a self-bound anisotropic superfluid with a superfluid fraction ρ s /ρ lower than 1 due to the corrugation of the adsorption potential. In the case of GF such corrugation is so large that ρ s /ρ=0.6 at T=0 K and the superfluid is essentially restricted to move in a multiconnected space, along the bonds of a honeycomb lattice. We predict a superfluid transition temperature T≠0.25 (1.1) K for 4He on GF (GH). We have studied the elementary excitation spectrum of 4He on GF at equilibrium density finding a phonon-maxon-roton dispersion relation that is strongly anisotropic in the roton region. We conclude that these new platforms for adsorption studies offer the possibility of studying novel superfluid phases of quantum condensed matter.

Original languageEnglish (US)
Pages (from-to)699-710
Number of pages12
JournalJournal of Low Temperature Physics
Volume171
Issue number5-6
DOIs
StatePublished - Jun 1 2013

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rotons
Graphite
Fluorides
Graphene
fluorides
graphene
Adsorption
Ground state
adsorption
Anisotropic fluids
anisotropic fluids
helium film
ground state
Helium
Substrates
Phase behavior
elementary excitations
Surface structure
Superconducting transition temperature
platforms

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Nava, M. ; Galli, D. E. ; Cole, Milton Walter ; Reatto, L. / Superfluid state of 4He on graphane and graphene-fluoride : Anisotropic roton states. In: Journal of Low Temperature Physics. 2013 ; Vol. 171, No. 5-6. pp. 699-710.
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Superfluid state of 4He on graphane and graphene-fluoride : Anisotropic roton states. / Nava, M.; Galli, D. E.; Cole, Milton Walter; Reatto, L.

In: Journal of Low Temperature Physics, Vol. 171, No. 5-6, 01.06.2013, p. 699-710.

Research output: Contribution to journalArticle

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