Dual-Sided Adsorption: Devil's Staircase of Coverage Fractions

Youjian Tang, Cheng Ing Chia, Vincent H. Crespi

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Abstract

By adsorbing the same species onto both sides of a suspended, atomically thin membrane, it is possible to couple two distinct surface adsorption systems. This new system, with reflection symmetry about the membrane, is described by a phase diagram with two axes, both representing the chemical potential of the same element, but in distinct half-spaces. For the case of potassium adsorption onto a graphene membrane, the result is a devil's staircase of fractions for the proportion of adsorbates adhered to one side. Fractions with simpler denominators are favored across wider regions of chemical potential, a pattern reminiscent of other fractional systems across a wide range of physics. Since the system can support multiple devil's staircases each at a distinct overall adsorbate areal density, points along the boundary between adjacent staircases can come arbitrarily close to violating the Gibbs phase rule. This dual-sided adsorbate geometry provides a means to explore surface science for pairs of weakly coupled surfaces.

Original languageEnglish (US)
Article number056101
JournalPhysical Review Letters
Volume120
Issue number5
DOIs
StatePublished - Jan 31 2018

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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