Superconductivity Induced By Aging And Annealing In K1-Delta Cr3as3hx

There has been a puzzling discrepancy on the physical property of quasi-one-dimensional Cr-based compound KCr3As3. While the polycrystalline KCr3As3 was originally reported to be nonsuperconducting with a spin-glass ground state, the single-crystalline KCr3As3 was later found to exhibit superconductivity at similar to 5 K. Here we demonstrate that both the polycrystals and single crystals can be made either nonsuperconducting or superconducting. The pristine samples show a spin-glass behavior only, and superconductivity below 5 K is actually induced by the post-aging and/or post-annealing. The result can be understood in terms of hydrogen intercalation into the one-dimensional Cr3As3 tubes, which was discovered very recently by K. M. Taddei et al. (arXiv:1905.03360). In addition, significant K deficiency and microscopic inhomogeneity have been revealed, suggesting a phase separation scenario with columnar superconductivity in K1-delta Cr3As3Hx. The possible processes of the hydrogen intercalation are given.