Electronic Structure and Linhard Function of Iron-Based Superconductor La0.5−xNa0.5 + xFe2As2

We perform theoretical studies of the iron-based superconductor La0.5−xNa0.5 + xFe2As2. Using density functional calculation with virtual crystal approximation, band structures, density of states, and Fermi surfaces are obtained for different La/Na composition by varying x value. Furthermore, the nesting property is also investigated using the Linhard function. Our main findings are as follows: For undoped (x = 0.0) case, the magnetic and electronic structure share great similarities with extensively studied BaFe2As2. Upon hole doping (x = 0.3), the Q = (π,π) nesting property are preserved. However, upon electron doping (x = -0.3), the Fermi surfaces undergo a dramastic change into 3D and complex structure. We find this change is attributed to the comprehensive influence of band filling and chemical pressure of La3+. We propose the asymmetric change of Fermi surfaces upon doping may in some sense explain the electron-hole asymmetry in phase diagram.