Enhancement of superconductivity in organic-inorganic hybrid topological materials

Inducing or enhancing superconductivity in topological materials has attracted extensive research interests partly due to its fundamental importance toward topological superconductivity. Reducing the thickness of transition metal dichalcogenides has provided an important pathway to engineer superconductivity in topological matters, emergent superconductivity with T_c ~ 0.82 K in monolayer WTe₂ which also hosts intriguing high-temperature quantum spin Hall effect. However, such monolayer samples are often difficult to obtain and extremely sensitive in air. Here we report a generic, experimentally convenient approach to manipulate the interlayer coupling in bulk MoTe₂ and WTe₂ single crystals through organic cation intercalation. The as-formed organic-inorganic hybrid crystals exhibit dramatically enhanced superconductivity with T_c of 7.0 K for intercalated MoTe₂ (as compared with 0.25 K for bulk crystal) and 2.3 K for intercalated WTe₂ (record high compared to monolayer WTe₂ and with greatly improved sample stability). This organic-cation-intercalation method can be readily applied to many other layered crystals, forming a promising research platform to manipulate their corresponding electronic states, including possible topological superconductivity with significantly enhanced T_c.