Extreme sensitivity of superconductivity to stoichiometry in Fe_{1+δ}Se

✍ Scribed by McQueen, T. M.; Huang, Q.; Ksenofontov, V.; Felser, C.; Xu, Q.; Zandbergen, H.; Hor, Y. S.; Allred, J.; Williams, A. J.; Qu, D.

• Book ID: 111859564
• Publisher: The American Physical Society
• Year: 2009
• Tongue: English
• Weight: 694 KB
• Volume: 79
• Category: Article
• ISSN: 1098-0121
• DOI: 10.1103/physrevb.79.014522

✦ Synopsis

The recently discovered iron arsenide superconductors appear to display a universal set of characteristic features, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe 1+␦ Se, which can be considered the parent compound of the superconducting arsenide family, is destroyed by very small changes in stoichiometry. Further, we show that nonsuperconducting Fe 1+␦ Se is not magnetically ordered down to 5 K. These results suggest that robust superconductivity and immediate instability against an ordered magnetic state should not be considered as intrinsic characteristics of iron-based superconducting systems.