2012/08/28 by Rong Yu, Qimiao Si
Physics and Astronomy · #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.110.146402
published as Phys. Rev. Lett. 110, 146402 (2013) · 6 pages, 5 figures, including supplementary information
arxiv created 2012/08/28 · arxiv updated 2013/04/22
We study a multiorbital model for the alkaline iron selenides K(1-x)Fe(2-y)Se2 using a slave-spin method. With or without ordered vacancies, we identify a metal-to-Mott-insulator transition at the commensurate filling of six 3d electrons per iron ion. For Hund's couplings beyond a threshold value, this occurs via an intermediate orbital-selective Mott phase, in which the 3d xy orbital is Mott localized while the other 3d orbitals remain itinerant. This phase is still stabilized over a range of carrier dopings. Our results lead to an overall phase diagram for the alkaline iron selenides, which provides a unified framework to understand the interplay between the strength of vacancy order and carrier doping. In this phase diagram, the orbital-selective Mott phase provides a natural link between the superconducting K(1-x)Fe(2-y)Se2 and its Mott-insulating parent compound.