Phase transitions and superconductivity of iron-based superconductors from first-principles

Publication date: Available online 20 February 2020Source: Physics Letters AAuthor(s): Shi-Yu Liu, Shang Liu, Shiyang Liu, De-Jun Li, Deependra Shah, Ruohanyang Leng, Sanwu WangAbstractFirst-principles calculations were performed to explore the atomic, electronic and superconductivity properties of the Ba1−x(K, Na)xFe2As2, LaFeAsO1−xFx and Ca1−xLaxFeAsH iron-based superconductors. The calculations show that the iron-based superconductors undergo structural and magnetic phase transitions from an orthorhombic antiferromagnetic (AFM) structure to a tetragonal structure when the impurity (K/Na/F/La) concentration increases, indicating that the impurity can suppress the AFM of the BaFe2As2, LaFeAsO and CaFeAsH compounds and then induce superconductivity under the K/Na/F/La-rich conditions, in agreement with experimental observations. In addition, the electronic band structures of the tetragonal iron-based superconductors show flat bands near the Fermi levels, and the superconductive transition temperature scales with the length of the flat band segment, consistent with the previous study on the cuprate superconductors. The mechanism of the iron-based superconductors is further understood with string theory.

Source: Physics Letters A - February 22, 2020 Category: Physics Source Type: research