Room-temperature superconductivity has been a long-held dream and an area of intensive research. Pressure comes to play an important role in stabilizing superconductive hydrides that become a hot topic in the field recently [1]. Exciting experimental discoveries [2,3] were recently made with the aid of theoretical searches [4,5] where the best ever-known superconductor of LaH10 with Tc reaching 260 K was reported.
In this talk, I will give an overview on the current status of research progress on superconductive hydrides, and then introduces the first-ever example of sodalite-like clathrate CaH6 that was predicted by my group in 2012 [6]. Later on, I will present our theoretical predictions of a wide range of high Tc sodalite-like clathrate rare earth (RE) hydrides with stoichiometries of REH6, REH9, and REH10 that can be achieved at high pressures [4,5]. This later prediction together with Ref. 4 stimulated the experimental discoveries of LaH10 with the measured Tc at ~260 K [2] and ~250 K [3], respectively. The scientific ideas on why we purposely choose RE hydrides and the general design principle for achieving high Tc superconductive hydrides will be discussed.
Before the end of the talk, I will present our very recent prediction on alternative clathrate structure in Li-Mg-H system [7] that has the calculated Tc at ~ 400 K, well beyond room-T. Experimental confirmation is apparently needed to verify this exciting prediction.
[1] L. Zhang, Y. Wang, J. Lv, and Y. Ma, Nat. Rev. Mater. 2, 17005 (2017).
[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 (2019).
[3] A. P. Drozdov et al., Nature 569, 528 (2019).
[4] F. Peng, Y. Sun, C. J. Pickard, R. J. Needs, Q. Wu, and Y. Ma, Phys. Rev. Lett. 119, 107001 (2017).
[5] H. Liu, Naumov, II, R. Hoffmann, N. W. Ashcroft, and R. J. Hemley, Proc. Natl. Acad. Sci. U S A 114, 6990 (2017).
[6] H. Wang, J. S. Tse, K. Tanaka, T. Iitaka, and Y. Ma, Proc. Natl. Acad. Sci. U S A 109, 6463 (2012).
[7] Y. Sun, J. Lv, H. Liu, Y. Xie, and Y. Ma, Phys. Rev. Lett. Submitted (2019).
*Email: mym@jlu.edu.cn; Webpage: http://mym.calypso.cn