Superconductivity in two-dimensional η-Mo3C2 films

Abstract

Two-dimensional (2D) superconductors have intriguing physical properties and abundant potential applications. Recently, 2D superconducting α-Mo 2 C and facecentered cubic Mo 2 C 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-Mo 3 C 2 films with different thicknesses, with the assistance of controllable plasma power. The grown η-Mo 3 C 2 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-Mo 3 C 2 ultrathin film, but also provides a convenient growth way to realize more carbide-based heterostructures for future device applications.

Strategies for Fabricating High‐Performance Electrochemical Energy‐Storage Devices by MXenes

“…because of its decreased resistance with an increase in the temperature, and the superconductivity transitions were observed for all the samples after carbonisation. [89] The authors also found that the transition temperature increased with the thickness of η-Mo 3 C 2 films (from 2.1 to 6.5 nm) though extremely thin films (with thickness below 2 nm) exhibited semiconducting behaviour. [89]…”

“…[89] The authors also found that the transition temperature increased with the thickness of η-Mo 3 C 2 films (from 2.1 to 6.5 nm) though extremely thin films (with thickness below 2 nm) exhibited semiconducting behaviour. [89]…”

“…MXenes with unique properties have been experimentally synthesised or theoretically predicted. These properties include tuneable band gap (the band gap of Ti 3 C 2 changes from 0.1 to 0.9 eV after Nb doping), [88] superconductivity (α-Mo 2 C and η-Mo 3 C 2 ), [89] high capacity (the specific capacity of Nb 2 CT x after the intercalation of Li + is~450 mAh g À 1 at 50 mA g À 1 ), [90] excellent tensile strength (670 MPa for Ti 3 C 2 sheets) [91] and so on. Therefore, it is necessary to understand the most important property of the material (i. e., the electrical conductivity) related to the fabrication of high-performance energy storage devices.…”

“…[121] In addition, Shi et al investigated the superconducting properties of η-Mo 3 C 2 films prepared by controllable carbonisation of molybdenum. [89] The pristine Mo film displayed semiconducting behaviour and temperature ranging from 300 to 800 K. [113] Reproduced with permission of Ref. [113].…”