Clathrate Superhydrides Under High Pressure: A Class of Extraordinarily Hot Conventional Superconductors

A Joint Seminar of the NOMAD Laboratory and of the Ma group

  • Online Seminar
  • Date: Aug 6, 2020
  • Time: 10:15
  • Speaker: Professor Yanming Ma
  • State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun, P. R. China
  • Location: https://us02web.zoom.us/j/81018080779?pwd=dXFlZXMzTi9JdElUTlM5MnhrNE5aZz09
  • Room: Webinar ID: 810 1808 0779 | Password: NOMAD
  • Host: Christian Carbogno
Clathrate Superhydrides Under High Pressure: A Class of Extraordinarily Hot Conventional Superconductors
In this talk, I will first give a short introduction to the research activities that have been carried out in my group in recent years and, then, give an overview on the current status of research progress on pressure-stabilized superhydrides that show near room-temperature superconductivity.

In 2012, we proposed a unconventional superhydride CaH61 in Ca-H system stabilized at extreme pressures via our in-house developed swarm-intelligence based CALYPSO method2-4 for structure prediction. CaH6 shows a potential of 235 K high superconductivity at 150 GPa and exhibits a unique clathrate type structure with Ca sitting at the center of hydrogen cage. Recently, we further predicted via CALYPSO a general phenomenon on the formation of clathrate structures at high pressure in rare earth (RE) superhydrides having stoichiometries of REH6, REH9, and REH10, some of which exhibit room-temperature superconductivity5.
Motivated by our theory, subsequent experiments synthesized the as-predicted clathrate YH6, YH9, and LaH10 with the measured Tc values reaching at 2246,7, 2437, and 260 K8,9, respectively, setting up Tc records among known superconductors. These discoveries might open up the door of achieving room-temperature superconductors among hydrogen-rich hydrides under high pressures.
In the end, I will discuss the design principle towards to achieving room-temperature superconductivity among superhydrides. As an example, our recent prediction on clathrate superhydride in Li-Mg-H ternary system10 with a predicted Tc at ~400 K will be discussed.

References:
1. Wang, H. et al., Proc. Natl. Acad. Sci. USA 109, 6463-6466 (2012).
2. Wang, Y. C. et al., Phys. Rev. B 82, 094116 (2010).
3. Wang, Y. C. et al., Comput. Phys. Commun. 183, 2063-2070 (2012).
4. Gao, B. et al., Science Bulletin 64, 301 (2019).
5. Peng, F. et al., Phys. Rev. Lett. 119, 107001 (2017).
6. Troyan, I. A. et al., arXiv 1908.01534 (2019).
7. Kong, P. P. et al., arXiv 1909.10482 (2019).
8. Drozdov, A. P. et al., Nature 569, 528-531 (2019).
9. Somayazulu, M. et al., Phys. Rev. Lett. 122, 027001 (2019).
10. Sun, Y. et al., Phys. Rev. Lett. 123, 097001 (2019).

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