Superconductivity in functionalized niobium-carbide MXenes

Abstract

We show the effect of Cl and S functionalization on the superconducting properties of layered (bulk) and monolayer niobium carbide (Nb${}_2$C) MXene crystals, based on first-principles calculations combined with Eliashberg theory. For the bulk layered Nb${}_2$CCl${}_2$, the calculated superconducting transition temperature ($T_c$) is in very good agreement with the recently measured value of 6 K. We show that $T_c$ is enhanced to 10 K for monolayer Nb${}_2$CCl${}_2$, due to an increase in the density of states at the Fermi level, and the corresponding electron-phonon coupling. We further demonstrate a feasible gate-induced enhancement of $T_c$ up to 40 K for both bulk-layered and monolayer Nb${}_2$CCl${}_2$ crystals. For the S-functionalized cases our calculations reveal the importance of phonon softening in understanding their superconducting properties. Finally, we predict that Nb${}_3$C${}_2$S${}_2$ in bulk-layered and monolayer form is potentially superconducting, with a $T_c$ around 30 K. Considering that Nb${}_2$C is not superconducting in pristine form, our findings promote functionalization as a pathway towards robust superconductivity in MXenes.

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Cited by in corpus (3)

• Full-bandwidth anisotropic Migdal-Eliashberg theory and its application to superhydrides
• Metal-to-superconductor Transition Induced by Lithium Adsorption on Monolayer 1$T$-Nb${}_2$C
• Exploring functionalized Zr${}_2$N and Sc${}_2$N MXenes as superconducting candidates with $\text{ab initio}$ calculations