Issue 14, 2017

Predicting stable phase monolayer Mo2C (MXene), a superconductor with chemically-tunable critical temperature

Abstract

Two-dimensional (2D) superconductors have attracted great attention in recent years due to the possibility of new phenomena in lower dimensions. With many bulk transition metal carbides being well-known conventional superconductors, here we perform first-principles calculations to evaluate the possible superconductivity in a 2D monolayer Mo2C. Three candidate structures (monolayer alpha-Mo2C, 1T MXene-Mo2C, and 2H MXene-Mo2C) are considered and the most stable form is found to be 2H MXene-Mo2C. Electronic structure calculations indicate that both unpassivated and passivated 2H forms exhibit metallic properties. We obtain phonon frequencies and electron–phonon couplings using density-functional perturbation theory, and based on the BCS theory and the McMillan equation, estimate the critical temperatures to be in the ∼0–13 K range, depending on the species of surface termination (O, H and OH). The optimal termination group is H, which can increase the electron–phonon coupling and bring the critical temperature to 13 K. This shows a rather high critical temperature, tunable by surface termination, making this 2D carbide an interesting test bed for low-dimensional superconductivity.

Graphical abstract: Predicting stable phase monolayer Mo2C (MXene), a superconductor with chemically-tunable critical temperature

Supplementary files

Article information

Article type
Communication
Submitted
29 Dec 2016
Accepted
06 Mar 2017
First published
06 Mar 2017

J. Mater. Chem. C, 2017,5, 3438-3444

Predicting stable phase monolayer Mo2C (MXene), a superconductor with chemically-tunable critical temperature

J. Lei, A. Kutana and B. I. Yakobson, J. Mater. Chem. C, 2017, 5, 3438 DOI: 10.1039/C7TC00789B

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