Fermiology of two-dimensional titanium carbide and nitride MXenes

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2021-07-07

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en

Pages

7

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Physical Review B, Volume 104, issue 3

Abstract

MXenes are a family two-dimensional transition-metal carbide and nitride materials, which often exhibit very good metallic conductivity and are thus of great interest for applications in, e.g., flexible electronics, electrocatalysis, and electromagnetic interference shielding. However, surprisingly little is known about the fermiology of MXenes, i.e., the shape and size of their Fermi surfaces, and its effect on the material properties. One reason for this may be that MXene surfaces are almost always covered by a mixture of functional groups, and studying Fermi surfaces of disordered systems is cumbersome. Here, we study fermiology of four common Ti-based MXenes as a function of the surface functional group composition. We first calculate the effective band structures of systems with explicit mixed surfaces and observe gradual evolution in the filling of the Ti-d band and resulting shift of Fermi level. We then demonstrate that these band structures can be closely approximated by using pseudohydrogenated surfaces, and also compare favorably to the experimental angle-resolved photoemission spectroscopy results. By modifying the pseudohydrogen charge we then proceed to plot Fermi surfaces for all systems and extract their properties, such as the Fermi-surface area and average Fermi velocity. These are in turn used to evaluate the electrical conductivity with the relaxation time fitted to experimentally measured conductivities.

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Funding Information: We thank Prof. N. Koch and Dr. T. Schultz for providing us the original ARPES data, previously published in Ref. . We are grateful to the Academy of Finland for support under Academy Research Fellow funding No. 311058. We also thank CSC–IT Center for Science Ltd. for generous grants of computer time. Publisher Copyright: © 2021 American Physical Society.

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Bagheri, M, Ibragimova, R & Komsa, H P 2021, ' Fermiology of two-dimensional titanium carbide and nitride MXenes ', Physical Review B, vol. 104, no. 3, 035408 . https://doi.org/10.1103/PhysRevB.104.035408