High-pressure sulfur frameworks in Mg-S compounds: Tuning superconductivity through covalent connectivity
Qianhui Wu, Aitor Bergara, Xiaohua Zhang, Guochun Yang
DOI 10.1103/PhysRevB.111.214501 · Physical Review B
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Abstract
Understanding the behavior of compounds with rich covalent connectivity under high pressure is crucial for advancing superconductor design. In this study, we identify two superconducting S-rich Mg-S compounds, P6/mmm MgS2 and I4/m MgS4, using first-principles structure search calculations under high-pressure conditions. These compounds exhibit unique three-dimensional S covalent networks, featuring honeycomblike and dual-channel structures formed by fivefold-connected trigonal bipyramid and sixfold-connected quasitriangular prism units of S atoms, respectively. The partial occupation of antibonding states and the involvement of S 3d orbitals contribute to the formation of weak S-S covalent bonds, which support these high-connectivity motifs. Furthermore, the superconducting properties of these sulfides are largely contributed by their S frameworks, with P6/mmm MgS2 achieving a Tc of 26.1 K at 300 GPa. This structural arrangement enhances the electronic density of states at the Fermi surface and softens acoustic phonon modes, enabling strong electron-phonon coupling. This work offers valuable insights for designing novel superconductors through precise manipulation of covalent bonding patterns.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| MgS2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 26.1 | 300 GPa | unknown |
| MgS4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 19 | 200 GPa | unknown |
| LuS6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 25.86 | 70 GPa | unknown |
| H3S Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 203 | 150 GPa | unknown |
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