117th CEMS Colloquium

講演者

清水 克哉 (大阪大学 教授)

日程

2023年11月29日(水) 17:30～18:30

開催場所

理化学研究所　大河内記念ホール

講演タイトル

ランタン系超伝導水素化物の合成実験

講演概要

Since the high-temperature superconductivity of hydrides was reported in hydrogen sulfide H3S [1],  many superconducting hydrides have been investigated by both theory and experiment. Comprehensive  theoretical studies have been made for binary hydrides consisting of a single metal element and hydrogen, and  verification experiments have been conducted based on these predictions. Among them, rare-earth-based  hydrides have attracted, for example, the lanthanum hydride (LaH10) was found to exhibit a superconducting  transition temperature (Tc) above 250 K at 150 GPa [2,3]. While higher superconducting transition temperatures  are expected to be obtained by adding light elements to rare earth hydrides, a realization of high-temperature  superconductivity at lower pressure (or ambient pressure) is aimed for future practical use.

Figure

Schematic drawing of the sample set in a diamond-anvil cell (left) and the microphotograph of the sample and electrodes taken through the diamond anvil (right).

We are now conducting experiments on the light-elements doping and substitution to rare earth hydrides.  The lanthanum-boron hydride, LaBH8 is the candidate with Tc ~ 138 K at ~ 70 GPa [4]. we have experimentally  verified the high-pressure synthesis of LaBH8 and its superconductivity. The details of the recent experimental  investigations for synthesis and observation of the hydrogen-rich superconductors will be reviewed.

References

  1. A. P. Drozdov, M. I. Eremets, I. A. Troyan, V. Ksenofontov, and S. I. Shylin, Nature, 525, 73 (2015).
  2. M. Somayazulu, M. Ahart, A. K. Mishra, Z. M. Geballe, M. Baldini, Y. Meng, V. V. Struzhkin, and R. J. Hemley, Phys. Rev. Lett., 122, 027001  (2018).
  3. A. P. Drozdov, P. P. Kong, V. S. Minkov, S. P. Besedin, M. A. Kuzovnikov, S. Mozaffari, L. Balicas, F. F. Balakirev, D. E. Graf, V. B.  Prakapenka, E. Greenberg, D. A. Knyazev, M. Tkacz, and M. I. Eremets, Nature, 569, 528 (2019).
  4. Z. Zhang, T. Cui, M. J. Hutcheon, A. M. Shipley, H. Song, M. Du, V. Z. Kresin, D. Duan, C. J. Pickard, and Y. Yao, Phys. Rev. Lett., 128,  047001 (2022).