117th CEMS Colloquium

Speaker

Prof. Katsuya Shimizu (Osaka University)

Date

17:30 - 18:30, November 29, 2023 (Wednesday)

Venue

Okochi-Hall, RIKEN

Title

Synthesis of Superconductive Lanthanum-Based Hydrides and Its Experimental Background

Abstract

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).