Phase Transition and Superconductivity Enhancement in Se-Substituted MoTe Thin Films.

Consecutively tailoring few-layer transition metal dichalcogenides MX from 2H to T phase may realize the long-sought topological superconductivity in a single material system by incorporating superconductivity and the quantum spin Hall effect together. Here, this study demonstrates that a consecutive structural phase transition from T to 1T' to 2H polytype can be realized by increasing the Se concentration in Se-substituted MoTe thin films. More importantly, the Se-substitution is found to dramatically enhance the superconductivity of the MoTe thin film, which is interpreted as the introduction of two-band superconductivity. The chemical-constituent-induced phase transition offers a new strategy to study the s superconductivity and the possible topological superconductivity, as well as to develop phase-sensitive devices based on MX materials.