Issue 46, 2020

Electronic, vibrational, and electron–phonon coupling properties in SnSe2 and SnS2 under pressure

Abstract

The tin-selenide and tin-sulfide classes of materials undergo multiple structural transitions under high pressure leading to periodic lattice distortions, superconductivity, and topologically non-trivial phases, yet a number of controversies exist regarding the structural transformations in these systems. We perform first-principles calculations within the framework of density functional theory and a careful comparison of our results with available experiments on SnSe2 reveals that the apparent contradictions among high-pressure results can be attributed to differences in experimental conditions. We further demonstrate that under hydrostatic pressure a Image ID:d0tc04356g-t1.gif superstructure can be stabilized above 20 GPa in SnS2via a periodic lattice distortion as found recently in the case of SnSe2, and that this pressure-induced phase transition is due to the combined effect of Fermi surface nesting and electron–phonon coupling at a momentum wave vector q = (1/3, 1/3, 0). In addition, we investigate the contribution of nonadiabatic corrections on the calculated phonon frequencies, and show that the quantitative agreement between theory and experiment for the high-energy A1g phonon mode is improved when these effects are taken into account. Finally, we examine the nature of the superconducting state recently observed in SnSe2 under nonhydrostatic pressure and predict the emergence of superconductivity with a comparable critical temperature in SnS2 under similar experimental conditions. Interestingly, in the periodic lattice distorted phases, the critical temperature is found to be reduced by an order of magnitude due to the restructuring of the Fermi surface.

Graphical abstract: Electronic, vibrational, and electron–phonon coupling properties in SnSe2 and SnS2 under pressure

Supplementary files

Article information

Article type
Paper
Submitted
11 Sept. 2020
Accepted
19 Okt. 2020
First published
20 Okt. 2020

J. Mater. Chem. C, 2020,8, 16404-16417

Author version available

Electronic, vibrational, and electron–phonon coupling properties in SnSe2 and SnS2 under pressure

G. P. Kafle, C. Heil, H. Paudyal and E. R. Margine, J. Mater. Chem. C, 2020, 8, 16404 DOI: 10.1039/D0TC04356G

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