Iron Superconductor Quandary (IMAGE) American Physical Society Caption Superconductivity appears to rely on very different mechanisms in two varieties of iron-based superconductors. Credit American Physical Society [Illustration: Alan Stonebraker] Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.