Bound state of a He-3 atom at the interface of crystal and superfluid He-4

TL;DR

This study uses Quantum Monte Carlo simulations to analyze the bound state of a He-3 atom at the interface of crystalline and superfluid He-4, revealing localization in a quasi-2D layer influenced by substrate attraction.

Contribution

First-principles Quantum Monte Carlo simulations are employed to characterize He-3 bound states at He-4 interfaces, highlighting their localization and dependence on substrate effects.

Findings

He-3 atoms localize in a quasi-2D layer between solid and superfluid He-4.

The bound state is influenced by substrate attraction and atomic exchanges.

The localization layer is not necessarily the first non-solid layer.

Abstract

The bound state of a He-3 atom at the interface between coexisting crystalline and superfluid phases of He-4 is studied theoretically by means of first principle Quantum Monte Carlo simulations. We consider both the case of a solid/superfluid He-4 interface, as well as that of a few solid layers of He-4 forming on an attractive substrate. It is observed that the He-3 bound state is sharply localized in a well-defined, quasi-2D layer of He-4 in the region intermediate between the solid and the liquid. The layer in which the He-3 atom resides displays an intriguing interplay of atomic localization and quantum-mechanical exchanges; is not necessarily the first "non-solid" layer, as suggested in previous studies, and it is affected by the attractive strength of the substrate.