Ion doped Helium nanodroplets: Supersolidity in finite systems

Supersolidity is an intriguing state of matter featuring the characteristics of a solid order and superfluid flow.

We show that this phenomenon can occur naturally in a finite system, i.e. an ion doped Helium nanodroplet.

In general, due to the strong ion-Helium interactions, solid shells of Helium clusters, i.e. snowballs, are formed close to the ion, while the reminder of Helium atoms are in liquid phase.

However, for large droplets we predict that a supersolid layer emerges between the snowball and the liquid one, where the Helium density exhibits a periodic modulation of the particle density on a spherically curved geometry.

To identify the different phases in large droplets, we developed an approach that combines density functional theory with the Gaussian time-dependent Hartree approach enabling us to address crystalized order as well as liquid phase on equal footing.

For small nanodroplets, we verify that the predictions of our approach are in excellent agreement with Path-Integral Monte Carlo calculations in the low temperature limit.