Superconductivity enhancement in phase-engineered molybdenum carbide/disulfide vertical heterostructures

Significance We demonstrate that engineering of two-dimensional molybdenum carbide/disulfide heterostructures can result in superconducting architectures with higher critical temperatures than that of pristine α-Mo2 C. We developed a gas-phase reaction approach for the heterostack formation via phase transitions, which involves short sulfurization times (1–5 min) of α-Mo2 C films. Heterostructures of α-Mo2 C and γ′-phase MoC1−x exhibit superconductivity with a higher critical temperature (T C ∼ 6.8 K) than the original Mo2 C crystal (T C ∼ 4.0 K). The distinct chemical composition and modified structure of the metastable γ′-MoC1−x phase present in the layered structure might lead to a higher interfacial density of states and increase in the frequency of the relevant phonon modes, thus contributing to the superconductivity and hence to a higherT C .