Electronic structure, topological phase transitions and superconductivity in (K,Cs)xFe2Se2
I. A. Nekrasov, M. V. Sadovskii
Institute for Electrophysics RAS, Ural Branch, 620016 Ekaterinburg, Russia
Abstract
We present LDA band structure of novel hole doped
high temperature superconductors (K) KxFe2Se2 and
CsxFe2Se2 and compare it with previously studied electronic structure
of isostructural FeAs superconductor BaFe2As2 (Ba122).
We show that stoichiometric KFe2Se2 and CsFe2Se2 have rather
different Fermi surfaces as compared with Ba122. However at about
60
of hole doping Fermi surfaces of novel materials closely resemble those
of Ba122. In between these dopings we observe a number of topological Fermi
surface transitions near the Γ point in the Brillouin zone.
Superconducting transition temperature Tc of new systems is apparently
governed by the value of the total density of states (DOS) at the Fermi level.