Interdependence of Spin Structure, Anion Height and Electronic Structure of BaFe_2As_2

摘要

Superconducting as well as other electronic properties of Fe-based superconductors are quite sensitive to the structural parameters specially, on anion height which is intimately related to z_(As), the fractional z co-ordinate of As atom. Due to presence of strong magnetic fluctuation in these Fe-based superconductors, optimized structural parameters (lattice parameters a, b, c) including z_(As) using density functional theory (DFT) under generalized gradient approximation (GGA) does not match experimental values accurately. In this work, we show that the optimized value of z_(As) is strongly influenced by the spin structures in the orthorhombic phase of BaFe_2As_2 system. We take all possible spin structures for the orthorhombic BaFe_2As_2 system and then optimize z_(As). Using these optimized structures we calculate electronic structures like density of states, band structures etc., for each spin configurations. From these studies we show that the electronic structure, orbital order which is responsible for structural as well as related to nematic transition, are significantly influenced by the spin structures.