Infrared studies of novel iron-based superconductors

The discovery of new iron-based superconductors last year has excited the scientific community. Besides copper oxides, this is the only other example of materials that superconduct at temperatures higher than 50 K. In this project we have used infrared spectroscopy to study the optical properties of FeTe$_{0.87}$S$_{0.13}$ at varies energy scales. We have also examined how the optical properties changed as a function of temperature and high magnetic fields (up to 18 Tesla). Our results show that the superconducting state in iron-based superconductors develops from unconventional normal state, without well defined quasiparticles. This demonstrates the potential of infrared spectroscopy to provide insight into the unique properties of these novel materials.