Density-functional calculations of the electronic structures and magnetism of the pnictide superconductors BaFeAs₂ and BaFeSb₂

We investigate the structural, electronic, and magnetic properties of the hypothetical compound BaFePn₂ (Pn=As and Sb), which is isostructural to the parent compound of the high-temperature superconductor LaFeAsO_1−xF_x. Using density-functional theory, we show that the Fermi surface, electronic structure, and spin-density wave instability of BaFePn₂ are very similar to the Fe-based superconductors. Additionally, there are very dispersive metallic bands of a spacer Pn layer, which are almost decoupled from FePn layer. Our results show that experimental study of BaFePn₂ can test the role of charge and polarization fluctuation as well as the importance of two dimensionality in the mechanism of superconductivity.