Percolating Superconductivity in Air-Stable Organic-Ion Intercalated MoS2

J. M. Pereira, D. Tezze, I. Niehues, Y. Asensio, H. Yang, L. Mester, S. Chen, F. Casanova, A. M. Bittner, M. Ormaza, F. Schiller, B. Martín-García, R. Hillenbrand, L. E. Hueso and M. Gobbi

Advanced Functional Materials 2208761 (2022)
When doped into a certain range of charge carrier concentrations, MoS2 departs from its pristine semiconducting character to become a strongly correlated material characterized by exotic phenomena such as charge density waves or superconductivity. However, the required doping levels are typically achieved using ionic-liquid gating or air-sensitive alkali-ion intercalation, which are not compatible with standard device fabrication processes. Here, the emergence of superconductivity and a charge density wave phase in air-stable organic cation intercalated MoS2 crystals are reported. By selecting two different molecular guests, it is shown that these correlated electronic phases depend dramatically on the intercalated cation, demonstrating the potential of organic ion intercalation to finely tune the properties of 2D materials. Moreover, it is found that a fully developed zero-resistance state is not reached in few-nm-thick flakes, indicating the presence of 3D superconductive paths that are severed by the mechanical exfoliation. This behavior is ascribed to an inhomogeneous charge carrier distribution, which is probed at the nanoscale using scanning near-field optical microscopy. The results establish organic-ion intercalated MoS2 as a platform to study the emergence and modulation of correlated electronic phases.