Comparative study of tetragonal and hexagonal FeSe: An orbital-selective scenario
Technische Universität Dresden, Institut für Physikalische Chemie und Elektrochemie - 01062 Dresden, Germany, EU
Accepted: 1 December 2010
In order to explore the reason why the hexagonal phase of FeSe is insulating, in contrast with tetragonal FeSe which is superconducting, we study a model that incorporates all orbitals of the Iron d-shell. It is found, within the local-density approximation plus dynamical mean-field theory (LDA+DMFT) that hexagonal FeSe resembles an orbital-selective insulating state. Basing ourselves on the good semiquantitative accord with a range of experimental data for tetragonal-FeSe superconductor, we show the intrinsic nature of the pseudogap state in these chalcogenide systems leading to an orbital-selective violation of the Landau–Fermi-liquid description at low temperatures. We discuss the pseudogap regime microscopically, along with the nature of the insulating state of hexagonal FeSe.
PACS: 74.70.-b – Superconducting materials other than cuprates / 72.15.-v – Electronic conduction in metals and alloys / 71.27.+a – Strongly correlated electron systems; heavy fermions
© EPLA, 2010