Electronic Structure of InCo2As2 and KInCo4As4: LDA + DMFT

A comparative analysis of the electronic structure obtained in the DFT/LDA and LDA + DMFT approaches of the possible isostructural analogues of iron superconductors InCo2As2 and KInCo4As4 with the electronic structure of the parent high-temperature superconductor system BaFe2As2 is carried out. It is established that in spite of the rather large value of the electron-electron correlations (local Coulomb interaction on the Co-3d shell U = 4.0 eV, the Hund exchange interaction J = 0.85 eV), in the considered systems a relatively small quasiparticle mass renormalization 1.2-1.35 at the Fermi level is observed. The correlation effects lead to the remarkable shift and compression of the spectrum below -0.8 eV. The band structure of InCo2As2 near the Fermi level is qualitatively similar to the previously studied BaCo2As2, and differs significantly from the band structure of BaFe2As2. In the KInCo4As4 system, the bands near the Fermi level resemble the band structure of BaFe2As2, and the Fermi surfaces have a similar topology. This indirectly points to the possibility of superconductivity in KInCo4As4. Also according to the results of LDA + DMFT calculations it is seen that with a rather small hole or electron doping in the KInCo4As4 system will experience topological Lifshitz transitions. We believe that the synthesis of the InCo2As2 and KInCo4As4 compounds considered in this paper is important for the study of superconductivity in this class of materials.

Automated summary

A comparative analysis of electronic structures of possible isostructural analogues of iron superconductors InCo2As2 and KInCo4As4 with BaFe2As2 was conducted using DFT/LDA and LDA + DMFT approaches. Results showed relatively small quasiparticle mass renormalization at the Fermi level, and significant shifts and compressions of the spectrum below -0.8 eV due to correlation effects. The band structure of InCo2As2 resembled BaCo2As2, while KInCo4As4 showed similarities with the band structure and Fermi surfaces of BaFe2As2, suggesting the possibility of superconductivity. Furthermore, LDA + DMFT calculations indicated topological Lifshitz transitions under hole or electron doping in KInCo4As4. The synthesis of InCo2As2 and KInCo4As4 compounds is crucial for studying superconductivity in this class of materials.