Time: Thursday, 19/Aug/2021: 9:00am - 9:50am Session Chair: Arthur Haozhe Liu |
Location: Terrace 2A 130 2nd floor |
Yanming Ma
Clathrate Superhydrides Under High Pressure Conditions: A Class of Extraordinarily Hot Conventional Superconductors
College of Physics, Jilin Univ., Changchun 130012, China
Room-temperature superconductivity has been a century long-held dream of mankind and a focus of intensive research. Recent progress on findings of room-temperature superconductors among superhydrides stabilized at high pressure conditions is remarkable. Focus is placed on a class of clathrate superhydrides, the best ever-known family of superconductors, that exhibit extraordinarily high-Tc superconductivity (e.g., Tc = 260 K for LaH10 [1-4]).
The first-ever clathrate structure in superhydride is proposed in CaH6 [5] by my group that shows a potential of high-Tc superconductivity at about 235 K. This clathrate structure accepts the emergence of unusual H cages, in which H atoms are weakly covalently bonded to one another, with Ca atoms occupying the centers of the cages. The high-Tc superconductivity is arising from the peculiar H clathrate structure.
We recently found a common rule of the formation of superconducting clathrate structures in rare earth (RE, e.g., Sc, Y, La, Ce, Pr., etc) superhydrides accompanying the occurrence of three different stoichiometries of REH6, REH9, and REH10, some of which exhibit extraordinarily high-Tc superconductivity [1]. Subsequent experiments [3,4,6,7] indeed synthesized the as-predicted clathrate superhydrides YH6, YH9, and LaH10 with measured Tc values at 224, 243, and 260 K, respectively, setting up new Tc records among known superconductors. These discoveries open the door of achieving superconductors that could work at room temperature (300 K) in superhydrides.
In the talk, I will give an overview on the status of research progress on superconductive superhydrides, and then discuss the design principle for achieving room-temperature superconductor. Our prediction on a hot superconductor (Tc at ~400 K) in a clathrate superhydride Li2MgH16 [8] together with future research direction will be discussed.
References:
[1] Peng et al., PRL 119, 107001 (2017).
[2] Liu et al., PNAS 114, 6990 (2017).
[3] Somayazulu et al., PRL 122, 027001 (2019).
[4] Drozdov et al., Nature 569, 528 (2019).
[5] Wang et al., PNAS 109, 6463 (2012).
[6] Kong et al., arXiv 1909.10482 (2019) ; Snider et al., PRL 126, 117003 (2021).
[7] Troyan et al., Adv. Mater. 33, 2006832 (2021).
[8] Sun et al., PRL 123, 097001 (2019).
