The new high-Tc Fe-based superconductors: what do we know about their electronic structure?

V. L. VILDOSOLA

Workshop; XII Giambiagi School; 2010

The very recent discovery of high-Tc superconductivity in FeAs -basedmaterials has triggered intensive research lately aimed at understanding theirelectronic properties. In particular, the first discovered compounds ofthese  kind of superconductors are the ROFeAs (with R a rare-earth). Theseoxyarsenides belong to a wider class of rare-earth oxypnictides RTPnO(where T is a transition metal and Pn = As or P).The evolution of Tc along the series is very interesting and gives severalclues about how to start studying these systems. While Tc in thephosphates is only of a few Kelvins, it jumps when P is replaced by As.Even more interesting, Tc gets doubled  when La is replaced by a 4f element (Ce, Pr, Nd, etc) in the Arsenide series.A possible correlation of this evolution with  changes in the structural propertieshave attracted particular interest.This talk will be about some important aspects of theelectronic structure and the Fermi surface of these systems and their sensitivity to small changes in the interatomic positions. Using first-principles full-potentialcalculations we investigate this sensitive dependence by contrasting inparticular LaFeAsO and LaFePO.