In response to observation (2015) of superconducting Tc ~ 200 K, in pressurized H3S by Drozov et al., I proposed a mechanism in 2015 [1]. Briefly, neutral spins of H atom clathrate network get RKKY coupled via conduction electrons, resulting in RVB spin liquid. The spin liquid subsystem feeds back and creates strong singlet pairing among conduction electrons and enable high Tc's. Large zero point fluctuations [2] of H atoms quantum melt competing H atom dimer orders. Nature seems to smile via recent experiments in hydrides [3]. We also bring to focus early theoretical work suggesting Kondo insulating state in LaH3 (Ng et al., 1997 and Eder et al., 1998).
[1] G. Baskaran, arXiv:1507.03921 (2015) and to be published.
[2] I. Errea, J. Phys.: Condens. Matter 34, 231501 (2022);
K.K. Ly and D.M. Ceperley, Phys. Rev., B106, 054106 (2022)
[3] C.Q. Din and D.M. Ceperley, Nature, 615, 221 (2023)