Ionic liquid gating induced self-intercalation of transition metal chalcogenides

Ionic liquids provide versatile pathways for controlling the structures and properties of quantum materials, for example, electrostatic gating of nanometer thick flakes, insertion or extraction of protons and oxygen ions in perovskite oxide films, and intercalation of large-sized cations from the ionic liquids into layered crystals [1]. In this talk, I will present a new controlling method using ionic liquids, where metals dissolved from layered transition metal dichalcogenides (TMDCs) are driven into the van der Waals gap, forming three-dimensional monochalcogenides [2]. Using PdTe₂ and NiTe₂ examples, we demonstrate the successful self-intercalation, turning them into high-quality PdTe and NiTe single crystals. Moreover, the monochalcogenides exhibit distinctive properties from dichalcogenides. For instance, the self-intercalation of PdTe₂ leads to the emergence of superconductivity in PdTe with a larger upper critical field than nominal samples grown using other methods. I will also discuss the physical insights for the self-intercalation mechanism and the possibilities for extending such self-intercalation method to other TMDCs.



[1] Haoxiong Zhang, et al., “Tailored Ising superconductivity in intercalated bulk NbSe₂ through dimensionality and carrier control”, Nat. Phys. 18, 1425-1430 (2022)

[2] Fei Wang^∗, Yang Zhang^∗, Zhijie Wang^∗, et al., Ionic liquid gating induced self-intercalation of transition metal chalcogenides, Nat. Commun. 14, 4945 (2023)