Tuning from Frustrated Magnetism to Superconductivity in Quasi-One-Dimensional KCr${}_3$As${}_3$ Through Hydrogen Doping

We report the charge doping of KCr${}_3$As${}_3$ via H intercalation. We show that the previously reported ethanol bath deintercalation of K${}_2$Cr${}_3$As${}_3$ to KCr${}_3$As${}_3$ has a secondary effect whereby H from the bath enters the quasi-one-dimensional Cr${}_6$As${}_6$ chains. Furthermore, we find that - contrary to previous interpretations - the difference between non-superconducting as-grown KCr${}_3$As${}_3$ samples and superconducting hydrothermally annealed samples is not a change in crystallinity but due to charge doping, with the latter treatment increasing the H concentration in the CrAs tubes effectively electron-doping the 133 compound. These results suggest a new stoichiometry KH${}_x$Cr${}_3$As${}_3$, that superconductivity arises from a suppressed magnetic order via a tunable parameter and pave the way for the first charge-doped phase diagram in these materials.