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. 2022 Aug 1;12(1):13198.
doi: 10.1038/s41598-022-17539-8.

Prediction of phonon-mediated superconductivity in new Ti-based M[Formula: see text]AX phases

E Karaca  1   2 , P J P Byrne  1 , P J Hasnip  1 , M I J Probert  1
Affiliations

Prediction of phonon-mediated superconductivity in new Ti-based M[Formula: see text]AX phases

E Karaca et al. Sci Rep. .

Abstract

A high-throughput computational method is used to predict 39 new superconductors in the Ti-based M[Formula: see text]AX phases, and the best candidates are then studied in more detail using density functional theory electron-phonon coupling calculations. The detailed calculations agree with the simple predictions, and Ti[Formula: see text]AlX (X: B, C and N) materials are predicted to have higher values of [Formula: see text] than any currently known hexagonal M[Formula: see text]AX phases. The electronic states at the Fermi level are dominated by the Ti 3d states. The choice of X (X: B, C and N) has a significant impact on the electronic density of states but not on the phonon characteristics. The electron-phonon coupling parameter for Ti[Formula: see text]AlX (X: B, C and N) was determined to be 0.685, 0.743 and 0.775 with a predicted [Formula: see text] of 7.8 K, 10.8 K and 13.0 K, respectively.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
For Ti2AX (A: Al, Ge and In; X: B, C and N), the results for Tc computed using μ∗= 0.13 using Migdal–Eliashberg theory are presented as red (X = B), blue (X = C) and magenta (X = N) squares, and the corresponding experimental data are displayed as black circles, with linear best fit to the theoretical values in red, blue and magenta dashed lines. Red, blue and magenta dashed lines represent a simple Fröhlich model for estimating superconducting transition temperature Tc. Full data in Tables 1 and 2.
Figure 2
Figure 2
Simple BCS theory analysis of the observed trends in Tc for Ti2AX (A: Al, Ge, In, and X: B, C, or N).
Figure 3
Figure 3
(a) The hexagonal crystal structure of Ti2AlX (X: B, C and N) , where blocks of Ti-X (X: B, C and N) (formed by edge-shared Ti6X (X: B, C and N) octahedra) are sandwiched with Al atomic sheets. (b) The hexagonal Brillouin zone for Ti2AlX (X: B, C and N).
Figure 4
Figure 4
The electronic band structure, the total and partial electronic local density of states and Fermi surface for the hexagonal phase of (a) Ti2AlB, (b) Ti2AlC and (c) Ti2AlN.
Figure 5
Figure 5
Phonon dispersion curves, total, partial vibrational density of states and the calculated electron-phonon spectral function α2F(ω) (red line) and the variation of the electron–phonon coupling parameter (blue line) with rising frequency λ(ω) of (a) Ti2AlB, (b) Ti2AlC and (c) Ti2AlN.
See this image and copyright information in PMC

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