Doping-induced superconductivity in the van der Waals superatomic crystal Re$_6$Se$_8$Cl$_2$

TL;DR

This study demonstrates that doping via Cl dissociation induces superconductivity in the two-dimensional superatomic crystal Re$_6$Se$_8$Cl$_2$, marking the first such observation in a van der Waals superatomic material.

Contribution

It introduces a novel chemical doping method to induce superconductivity in van der Waals superatomic crystals, expanding the potential for electronic applications.

Findings

Doping transforms Re$_6$Se$_8$Cl$_2$ from semiconductor to superconductor.

Superconductivity observed below approximately 9 K.

Doping achieved through Cl dissociation using in situ current annealing.

Abstract

Superatomic crystals are composed of discrete modular clusters that emulate the role of atoms in traditional atomic solids$^{1-4}$. Owing to their unique hierarchical structures, these materials are promising candidates to host exotic phenomena, such as superconductivity and magnetism that can be revealed through doping$^{5-10}$. Low-dimensional superatomic crystals hold great promise as electronic components$^{11,12}$, enabling these properties to be applied to nanocircuits, but the impact of doping in such compounds remains unexplored. Here we report the electrical transport properties of Re$_6$Se$_8$Cl$_2$, a two-dimensional superatomic semiconductor$^{13,14}$. Using an in situ current annealing technique, we find that this compound can be n-doped through Cl dissociation, drastically altering the transport behaviour from semiconducting to metallic and giving rise to superconductivity below $\sim$ 9 K. This work is the first example of superconductivity in a van der Waals (vdW) superatomic crystal; more broadly, it establishes a new chemical strategy to manipulate the electronic properties of vdW materials with labile ligands.