Hydrogen Clathrate Structures in Rare Earth Hydrides at High Pressures: Possible Enroute to Room-temperature Superconductivity

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Peng, F 
Sun, Y 
Pickard, CJ 
Needs, RJ 
Wu, Q 

Room-temperature superconductivity has been a long-held dream and an area of intensive research. Recent experimental findings of superconductivity at 200 K in highly compressed hydrogen (H) sulfides have demonstrated the potential for achieving room-temperature superconductivity in compressed H-rich materials. We report first-principles structure searches for stable H-rich clathrate structures in rare earth hydrides at high pressures. The peculiarity of these structures lies in the emergence of unusual H cages with stoichiometries H24, H29, and H32, in which H atoms are weakly covalently-bonded to one another, with rare earth atoms occupying the centers of the cages. We have found that high-temperature superconductivity is closely associated with H clathrate structures with large H-derived electronic densities of states at the Fermi level and strong electron-phonon coupling related to the stretching and rocking motions of H atoms within the cages. Strikingly, a Yttrium (Y) H32 clathrate structure of stoichiometry YH10 is predicted to be a potential room-temperature superconductor with an estimated Tc of up to 303 K at 400 GPa, as derived by direct solution of the Eliashberg equation.

0912 Materials Engineering, 0302 Inorganic Chemistry
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Physical Review Letters
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American Physical Society
Royal Society (WM150023)
Engineering and Physical Sciences Research Council (EP/J017639/1)
Engineering and Physical Sciences Research Council (EP/P022596/1)
Engineering and Physical Sciences Research Council (EP/F032773/1)
We acknowledge funding support from Science Challenge Project at Grant No. TZ2016001, the National Natural Science Foundation of China under Grant No. 11534003, and the National Key Research and Development Program of China under Grant No. 2016YFB0201200. We also thank China Postdoctoral Science Foundation under Grant No. 2016M590033, the Natural Science Foundation of Henan Province Grant No. 162300410199, the Program for Science and Technology Innovation Talents in University of Henan Province Grant No. 17HASTIT015, and the Open Project of the State Key Laboratory of Superhard Materials, Jilin University, under Grant No. 201602. R. J. N. acknowledges funding from the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant No. EP/J017639/1. C. J. P. is supported by a Royal Society Wolfson Research Merit Award. Computational resources were provided by the high performance computing center of Jilin University, Tianhe2-JK in the Beijing Computational Science Research Center, the High Performance Computing Service at the University of Cambridge, and the ARCHER facility of the UK’s national high-performance computing service, for which access was obtained via the UKCP consortium (Grant No. EP/P022596/1).