Thin helium film on a glass substrate

TL;DR

This study uses Monte Carlo simulations to analyze the structure, energetics, and superfluid behavior of thin helium-4 films on glass, revealing a solid first layer and liquid subsequent layers, with helium-3 impurities residing on the outermost layer.

Contribution

It provides detailed simulation-based insights into the layering, phase behavior, and impurity localization in thin helium films on glass substrates.

Findings

First layer is solid and inert.

Subsequent layers are liquid with no clear separation.

Helium-3 impurities stay on the outermost layer.

Abstract

We investigate by Monte Carlo simulations the structure, energetics and superfluid properties of thin helium-four films (up to four layers) on a glass substrate, at low temperature. The first adsorbed layer is found to be solid and "inert", i.e., atoms are localized and do not participate to quantum exchanges. Additional layers are liquid, with no clear layer separation above the second one. It is found that a single helium-three impurity resides on the outmost layer, not significantly further away from the substrate than helium-four atoms on the same layer.