Why iron-based superconductors work

Science : The first superconductors were discovered in 1911. Half a century passed before physicists came up with a theory that could explain why some compounds had zero resistance at a few degrees above absolute zero . In 1986, researchers discovered complex compounds nicknamed " cuprates ” containing copper and oxygen that become superconductors at much higher “critical temperatures"—now as high as 138 kelvin , but couldn’t explain how or why they worked.In the last couple of years, researchers have discovered a new type, four families of iron-based superconductors with distinct crystal structures, that superconduct at temperatures as high at 27 Kelvin. Using tools honed on the cuprates they have made measurements that took decades to achieve in the older materials.More importantly, although physicists cannot say exactly how the iron-based superconductors work, they have developed a scheme that many say captures the essence of what’s going on. “We don’t have a full solution yet,” says MIT theorist Patrick Lee , “but the situation is better than in the cuprates."In fact, the emerging portrait of the iron-based superconductors jibes with some theories of the cuprates and seems to undermine more-exotic alternatives. So if physicists are on the right track with the iron-based superconductors, then the cuprates may not be so inscrutable after all.