Anomalous metallic phase in molybdenum disulphide induced via gate-driven organic ion intercalation

TL;DR

This study uses ionic gating to intercalate organic ions into MoS2, inducing a metallic phase with charge-density wave anomalies and revealing competition between metallic and superconducting states.

Contribution

It demonstrates a gate-driven organic ion intercalation method to induce and study an anomalous metallic phase in MoS2 without altering its crystal symmetry.

Findings

Induced a re-entrant insulator-to-metal transition in MoS2.

Observed charge-density wave anomalies at around 150 K.

No superconductivity detected down to 3 K.

Abstract

Transition metal dichalcogenides exhibit rich phase diagrams dominated by the interplay of superconductivity and charge density waves, which often result in anomalies in the electric transport properties. Here, we employ the ionic gating technique to realize a tunable, non-volatile organic ion intercalation in bulk single crystals of molybdenum disulphide (MoS$_{2}$). We demonstrate that this gate-driven organic ion intercalation induces a strong electron doping in the system without changing the pristine $2H$ crystal symmetry and triggers the emergence of a re-entrant insulator-to-metal transition. We show that the gate-induced metallic state exhibits clear anomalies in the temperature dependence of the resistivity with a natural explanation as signatures of the development of a charge-density wave phase which was previously observed in alkali-intercalated MoS$_{2}$. The relatively large temperature at which the anomalies are observed ($\sim$$150$ K), combined with the absence of any sign of doping-induced superconductivity down to $\sim$$3$ K, suggests that the two phases might be competing with each other to determine the electronic ground state of electron-doped MoS$_2$.