What superconducts in sulfur hydrides under pressure, and why
| Autor: | Bernstein, N., Hellberg, C. S., Johannes, M. D., Mazin, I. I., Mehl, M. J. |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 91, 060511 (2015) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.91.060511 |
| Popis: | The recent discovery of superconductivity at 190~K in highly compressed H$_{2}$S is spectacular not only because it sets a record high critical temperature, but because it does so in a material that appears to be, and we argue here that it is, a conventional strong-coupling BCS superconductor. Intriguingly, superconductivity in the observed pressure and temperature range was predicted theoretically in a similar compound H$_{3}$S. Several important questions about this remarkable result, however, are left unanswered: (1) Does the stoichiometry of the superconducting compound differ from the nominal composition, and could it be the predicted H$_{3}$S compound? (2) Is the physical origin of the anomalously high critical temperature related only to the high H phonon frequencies, or does strong electron-ion coupling play a role? We show that at experimentally relevant pressures H$_2$S is unstable, decomposing into H$_3$S and S, and that H$_3$S has a record high $T_c$ due to its covalent bonds driven metallic. The main reason for this extraordinarily high $T_c$ in H$_3$S as compared with MgB$_2$, another compound with a similar superconductivity mechanism, is the high vibrational frequency of the much lighter H atoms. Comment: Supplementary material contains crystallographic information |
| Databáze: | arXiv |
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