High $T_{\rm c}$ Superconductivity in Heavy Rare Earth Hydrides
Hao Song1, Zihan Zhang1, Tian Cui2,1*, Chris J. Pickard3,4, Vladimir Z. Kresin5, and Defang Duan1*
1State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China 2Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China 3Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom 4Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan 5Lawrence Berkeley Laboratory, University of California at Berkeley, Berkeley, CA 94720, USA
Abstract：Sulfur and lanthanum hydrides under compression display superconducting states with high observed critical temperatures. It has been recently demonstrated that carbonaceous sulfur hydride displays room temperature superconductivity. However, this phenomenon has been observed only at very high pressure. Here, we theoretically search for superconductors with very high critical temperatures, but at much lower pressures. We describe two of such sodalite-type clathrate hydrides, YbH$_{6}$ and LuH$_{6}$. These hydrides are metastable and are predicted to superconduct with $T_{\rm c} \sim 145$ K at 70 GPa and $T_{\rm c} \sim 273$ K at 100 GPa, respectively. This striking result is a consequence of the strong interrelationship between the $f$ states present at the Fermi level, structural stability, and the final $T_{\rm c}$ value. For example, TmH$_{6}$, with unfilled 4$f$ orbitals, is stable at 50 GPa, but has a relatively low value of $T_{\rm c}$ of 25 K. The YbH$_{6}$ and LuH$_{6}$ compounds, with their filled $f$-shells, exhibit prominent phonon “softening”, which leads to a strong electron-phonon coupling, and as a result, an increase in $T_{\rm c}$.
. [J]. 中国物理快报, 2021, 38(10): 107401-107401.
Hao Song, Zihan Zhang, Tian Cui, Chris J. Pickard, Vladimir Z. Kresin, and Defang Duan. High $T_{\rm c}$ Superconductivity in Heavy Rare Earth Hydrides. Chin. Phys. Lett., 2021, 38(10): 107401-107401.
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