Iron is a ferromagnetic metal, and ferromagnetism and superconductivity are generally mutually exclusive. Therefore the discovery of superconductivity in Fe-pnictide (pnictide = As, P) compounds in 2008 with high transition temperatures Tc up to 56 K was a welcome shock to the CMP community. Experimental and theoretical studies carried out over the past five years that help to explain this puzzle will be discussed. The results strongly point to an unconventional magnetic mechanism for high-Tc superconductivity in the Fe-pnictides, just as is generally believed to be the case in the layered copper oxides discovered in 1986 that have Tc’s up to 164 K, despite the large differences between these two types of materials. Our recent studies of compounds that we synthesized in an attempt to discover new, but related, high-Tc superconductors will also be discussed.
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