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Title: Is sodium a superconductor under high pressure?

Superconductivity has been predicted or measured for most alkali metals under high pressure, but the computed critical temperature (T c) of sodium (Na) at the face-centered cubic (fcc) phase is vanishingly low. Here we report a thorough, first-principles investigation of superconductivity in Na under pressures up to 260 GPa, where the metal-to-insulator transition occurs. Linear-response calculations and density functional perturbation theory were employed to evaluate phonon distributions and the electron-phonon coupling for bcc, fcc, cI16, and tI19 Na. Our results indicate that the maximum electron-phonon coupling parameter, λ, is 0.5 for the cI16 phase, corresponding to a theoretical peak in the critical temperature at T c ≈ 1.2 K. When pressure decreases or increases from 130 GPa, T c drops quickly. This is mainly due to the lack of p-d hybridization in Na even at 260 GPa. Since current methods based on the Eliashberg and McMillian formalisms tend to overestimate the Tc (especially the peak values) of alkali metals, we conclude that under high pressure—before the metal-to-insulator transition at 260 GPa—superconductivity in Na is very weak, if it is measurable at all.
Authors:
ORCiD logo [1] ;  [2] ;  [1]
  1. Colorado School of Mines, Golden, CO (United States). Dept. of Physics
  2. Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.
Publication Date:
Grant/Contract Number:
SC0006433
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 1; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Colorado School of Mines, Golden, CO (United States). Dept. of Physics
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1465370
Alternate Identifier(s):
OSTI ID: 1361719