Superconductivity in two-dimensional η-Mo3C2 films

Two-dimensional (2D) superconductors have intriguing physical properties and abundant potential applications. Recently, 2D superconducting α-Mo2C and face-centered cubic Mo2C have been controllably prepared and they bring new viewpoints to carbon-based superconductivity. Although molybdenum carbides (Mo-Cs) have multiple crystalline stacking orders, there are still few structures reported for the lack of higher energy supply during growth. In this study, we report a two-step vapor deposition method to grow superconducting η-Mo3C2 films with different thicknesses, with the assistance of controllable plasma power. The grown η-Mo3C2 films show polycrystalline characteristics, but they still present superior superconductivity. The 3.0-nm-thick film has the superconducting transition temperature of 5.38 K , and its electrical performances follow truly 2D superconducting transitions. This study will not only exhibit a robust superconducting η-Mo3C2 ultrathin film, but also provides a convenient growth way to realize more carbide-based heterostructures for future device applications.