1Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 2Center for High Pressure Science & Technology Advanced Research, Beijing 100094, China 3School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
Abstract：Recently, the theoretically predicted lanthanum superhydride, LaH$_{10 \pm \delta}$, with a clathrate-like structure was successfully synthesized and found to exhibit a record high superconducting transition temperature $T_{\rm c} \approx 250$ K at $\sim $170 GPa, opening a new route for room-temperature superconductivity. However, since in situ experiments at megabar pressures are very challenging, few groups have reported the $\sim $250 K superconducting transition in LaH$_{10 \pm \delta}$. Here, we establish a simpler sample-loading procedure that allows a relatively large sample size for synthesis and a standard four-probe configuration for resistance measurements. Following this procedure, we successfully synthesized LaH$_{10 \pm \delta}$ with dimensions up to $10 \times 20$ μm$^{2}$ by laser heating a thin La flake and ammonia borane at $\sim $1700 K in a symmetric diamond anvil cell under the pressure of 165 GPa. The superconducting transition at $T_{\rm c} \approx 250$ K was confirmed through resistance measurements under various magnetic fields. Our method will facilitate explorations of near-room-temperature superconductors among metal superhydrides.
Flores-Livas J A, Boeri L, Sanna A, Profeta G, Arita R and Eremets M 2020 Phys. Rep.856 1
[4]
Uchida S I 2015 High Temperature Superconductivity: The Road to Higher Critical Temperature in Springer Series in Materials Science vol 213 (Berlin: Springer)
Kong P, Minkov V, Kuzovnikov M, Besedin S, Drozdov A, Mozaffari S, Balicas L, Balakirev F, Prakapenka V and Greenberg E 2019 arXiv:1909.10482 [cond-mat.supr-con]
[23]
Semenok D V, Kvashnin A G, Ivanova A G, Svitlyk V, Fominski V Y, Sadakov A V, Sobolevskiy O A, Pudalov V M, Troyan I A and Oganov A R 2020 Mater. Today33 36
2020, Vol. 37 
