Seminar: Peter Hirschfeld – University of Copenhagen

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Seminar: Peter Hirschfeld

Title: Why is the simplest Fe-based superconductor the strangest? 

Some clues from disorder experiments.

FeSe has the simplest structure of all the Fe-based superconductors, and a modest Tc of only 9K.  However almost any modification: pressure, intercalation, deposition of a single layer on SrTiO3, raises Tc to 40K and sometimes to the 70K or above.  Theories abound, but a consensus has not been reached in the community.  Very recently, it has been shown that atomic scale defects created by electron irradiation enhances Tc rather than suppressing it, as in all other Fe-based systems.  I will introduce general ideas about the role of disorder in unconventional superconductors, and then within this framework  consider various possible explanations for this experiment.  Finally, I'll discuss its implications for theories of FeSe.