Superconductivity by doping in alkali-metal hydrides without applied pressure: An ab initio study
M. A. Olea-Amezcua, O. De la Peña-Seaman, R. Heid
DOI 10.1103/PhysRevB.99.214504 · Physical Review B
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Abstract
The electronic, lattice dynamical, electron-phonon coupling, and superconducting properties of alkali-metal hydrides LiH, NaH, and KH, metalized through doping with alkaline-earth metals Be, Mg, and Ca, respectively, are investigated within the framework of density functional perturbation theory. The alloys were modeled by the self-consistent virtual crystal approximation, and the effect of zero-point energy contribution is consistently taken into account. For all three alloys, a steady increase of the electron-phonon coupling constant λ is found with progressive alkaline-earth metal doping, reaching values as high as 0.47 for (Li/Be)H, 1.26 for (Na/Mg)H, and 1.69 for (K/Ca)H. The growth of λ with doping is the result of two effects: the softening of the phonon spectrum, mainly of the H-optical modes, and the increase of the density of states at the Fermi level. Estimates of the superconducting critical temperature reach values of 2.1 K for Li0.95Be0.05H, 28 K for Na0.8Mg0.2H, and even 49 K for K0.55Ca0.45H, demonstrating that doping is an alternative route to high transition temperatures in this material class without the need to apply high external pressure.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Li0.95Be0.05H Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 2.1 | Pressure unresolved | unknown |
| Na0.8Mg0.2H Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28 | Pressure unresolved | unknown |
| K0.55Ca0.45H Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 49 | Pressure unresolved | unknown |
| H3S Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 203 | 200 GPa | unknown |
| SiH4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 166 | 202 GPa | unknown |
| GeH4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 64 | 220 GPa | unknown |
| H4Te Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 104 | 170 GPa | unknown |
| AcH10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 227.5 | 200 GPa | unknown |
| MgH12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 53.5 | 140 GPa | unknown |
| MgSiH6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 63 | 250 GPa | unknown |
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