2015/04/14 by Jeonghwan Ahn, Ahn, Jeonghwan, Sungjin Park +5
Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.1504.03531
arxiv created 2015/04/15 · arxiv updated 2015/04/16
Path-integral Monte Carlo calculations have been performed to study the 4He adsorption on both sides of a single α-graphyne sheet. For investigation of the interlayer correlation between the upper and the lower monolayer of 4He adatoms, the 4He-substrate interaction is described by the sum of the 4He-C interatomic pair potentials, for which we use both Lennard-Jones and Yukawa-6 anisotropic potentials. When the lower 4He layer is a C4/3 commensurate solid, the upper-layer 4He atoms are found to form a Kagomé lattice structure at a Mott insulating density of 0.0706 Å-2, and a commensurate solid at an areal density of 0.0941 Å-2 for both substrate potentials. The correlation between upper- and lower-layer pseudospins, which were introduced in Ref. [1] for two degenerate configurations of three 4He atoms in a hexagonal cell, depends on the substrate potential used; With the substrate potential based on the anisotropic Yukawa-6 pair potentials, the Ising pseudo-spins of both 4He layers are found to be anti-parallel to each other while the parallel and anti-parallel pseudo-spin alignments between the two 4He layers are nearly degenerate with the Lennard-Jones potentials. This is attributed to the difference in the interlayer distance, which is ∼ 4 Å~ with the Yukawa-6 substrate potential but as large as ∼ 4.8 Å~with the Lennard-Jones potential. [1] Y. Kwon, H. Shin, and H. Lee, Phys. Rev. B 88, 201403(R) (2013)