Potential high-<i>T<sub>c</sub></i> superconducting lanthanum and yttrium hydrides at high pressure.

Liu, Hanyu; Naumov, Ivan I; Hoffmann, Roald; Ashcroft, N W; Hemley, Russell J · Proc Natl Acad Sci U S A · 2017

basic_science · Level V

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Abstract

A systematic structure search in the La-H and Y-H systems under pressure reveals some hydrogen-rich structures with intriguing electronic properties. For example, LaH<sub>10</sub> is found to adopt a sodalite-like face-centered cubic (fcc) structure, stable above 200 GPa, and LaH<sub>8</sub> a <i>C</i>2/<i>m</i> space group structure. Phonon calculations indicate both are dynamically stable; electron phonon calculations coupled to Bardeen-Cooper-Schrieffer (BCS) arguments indicate they might be high-<i>T</i><sub><i>c</i></sub> superconductors. In particular, the superconducting transition temperature <i>T</i><sub><i>c</i></sub> calculated for LaH<sub>10</sub> is 274-286 K at 210 GPa. Similar calculations for the Y-H system predict stability of the sodalite-like fcc YH<sub>10</sub> and a <i>T</i><sub><i>c</i></sub> above room temperature, reaching 305-326 K at 250 GPa. The study suggests that dense hydrides consisting of these and related hydrogen polyhedral networks may represent new classes of potential very high-temperature superconductors.