Manifestations of Local Supersolidity of ${}^4$He around a Charged Molecular Impurity

Abstract

A frozen, solid helium core, dubbed snowball, is typically observed around cations in liquid helium. Here we discover, using path integral simulations, that around a cationic molecular impurity, protonated methane, the ${}^4$He atoms are indeed strongly localized akin to snowballs but still participate in vivid bosonic exchange induced by the ro-vibrational motion of the impurity. Such combination of solid-like order with pronounced superfluid response in the first helium shell indicates that manifestations of local supersolid behavior of ${}^4$He can be induced -- and probed experimentally -- by charged molecules.