Abstract
The ternary iron arsenide becomes superconducting by hole doping, which was achieved by partial substitution of the barium site with potassium. We have discovered bulk superconductivity at in with . The parent compound crystallizes in the tetragonal -type structure, which consists of iron arsenide layers separated by ions. is a poor metal and exhibits a spin density wave anomaly at 140 K. By substituting for ions we have introduced holes in the layers, which suppress the anomaly and induce superconductivity. The of 38 K in is the highest in hole doped iron arsenide superconductors so far. Therefore, we were able to expand this class of superconductors by oxygen-free compounds with the -type structure.
- Received 29 May 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.107006
©2008 American Physical Society