The annual meeting of the American Physical Society in March 2008 was especially memorable for condensed-matter physicists. It seemed that all anyone wanted to talk about in New Orleans was the surprising discovery, and subsequent confirmation, of high-temperature superconductivity in the iron arsenides.1 Surprising was perhaps an understatement. After all, iron was supposed to be as toxic to superconductivity as arsenic is to humans. The superconducting transition temperature Tc had reached only 26 K by the time of the March Meeting, though reports were circulating that—as with high-Tc cuprates two decades earlier—the application of high pressures was pushing Tc to temperatures above 40 K. The race was on.
In a matter of weeks after the meeting, substitutional studies had helped to repeatedly break the Tc record, which eventually plateaued at 56 K. As a barometer of the excitement, by the end of 2010, 8...
