Superconductivity induced by gate-driven hydrogen intercalation in the charge-density-wave compound 1T-TiSe2

The key role played by hydrogen (H) in the near-to-room temperature superconductivity of hydrides at megabar pressures suggests that H doping could produce similar effects in materials at ambient pressure. Here the authors show that ionic gate-driven H intercalation in the layered compound TiSe2 induces a superconducting phase with features distinct from those obtained through other doping techniques. Hydrogen (H) plays a key role in the near-to-room temperature superconductivity of hydrides at megabar pressures. This suggests that H doping could have similar effects on the electronic and phononic spectra of materials at ambient pressure as well. Here, we demonstrate the non-volatile control of the electronic ground state of titanium diselenide (1T-TiSe2) via ionic liquid gating-driven H intercalation. This protonation induces a superconducting phase, observed together with a charge-density wave through most of the phase diagram, with nearly doping-independent transition temperatures. The H-induced superconducting phase is possibly gapless-like and multi-band in nature, in contrast with those induced in TiSe2 via copper, lithium, and electrostatic doping. This unique behavior is supported by ab initio calculations showing that high concentrations of H dopants induce a full reconstruction of the bandstructure, although with little coupling between electrons and high-frequency H phonons. Our findings provide a promising approach for engineering the ground state of transition metal dichalcogenides and other layered materials via gate-controlled protonation.

Automated summary

In this study, the authors demonstrate a unique superconducting phase induced by ionic liquid gating-driven hydrogen intercalation in the layered compound TiSe2. The findings suggest that hydrogen doping could produce similar effects on the electronic and phononic spectra of materials at ambient pressure as it does in near-to-room temperature superconductivity of hydrides at megabar pressures. The non-volatile control of the electronic ground state of TiSe2 via gate-controlled protonation provides a promising approach for engineering the ground state of transition metal dichalcogenides and other layered materials.