James C. McGroddy Prize Talk: Progress in high-temperature conventional superconductivity

We studied the state of matter under extreme conditions and found new phenomena and
materials, including polymeric nitrogen, transparent sodium, electrically conducting
hydrogen, and superconductivy in various substances. Room-temperature superconductivity
is becoming realistic given dramatic progress in conventional superconductivity: the critical
temperature is Tc =203 K in H3S under high pressures of about 150 GPa1. We found even higher, nearly room temperature superconductivity in superhydride LaH10 2,3 with Tc 250 K, following the theoretical predictions4,5. This and yttrium and calcium superhydrides can be considered as a close realization of metallic hydrogen6.

We will discuss prospects for further increase of Tc to room temperature, which
naturally is expecting for hydrides at high pressures. We will present recent studies on YHx
and other compounds that are considered as potential room-temperature superconductors. We
will consider various directions to explore high-temperature conventional superconductivity
at low and ambient pressures.
1 Drozdov, A. P., Eremets, M. I., Troyan, I. A., Ksenofontov, V. & Shylin, S. I. Conventional
superconductivity at 203 K at high pressures. Nature 525, 73 (2015).
2 Drozdov, A. P. et al. Superconductivity at 250 K in lanthanum hydride under high pressures
Nature (2019).
3 Somayazulu, M. et al. Evidence for Superconductivity above 260 K in Lanthanum
Superhydride at Megabar Pressures. Phys. Rev. Lett. 122 027001 (2019).
4 Peng, F. et al. Hydrogen Clathrate Structures in Rare Earth Hydrides at High Pressures:
Possible Route to Room-Temperature Superconductivity. Phys. Rev. Lett. 119 107001 (2017).
5 Liu, H., Naumov, I. I., Hoffmann, R., Ashcroft, N. W. & Hemley, R. J. Potential high-Tc
superconducting lanthanum and yttrium hydrides at high pressure. PNAS 114, 6990 (2017).
6 Ashcroft, N. W. Metallic hydrogen: A high-temperature superconductor? Phys. Rev. Lett. 21,
1748-1750 (1968).