Ab-initio investigation of the electronic structure in the superconducting EuFe2(As1−xPx)2

The electronic structure and magnetic properties of EuFe2(As1−xPx)2 were investigated by means the local spin density approximation (LSDA) with the on-site Hubbard Ueff parameter (LSDA+U). The charge and spin densities, densities of states, band structures and Fermi surfaces as a function of the phosphorus percentage in the ferromagnetic tetragonal EuFe2(As1−xPx)2 have been presented and discussed. For all studied concentrations, our alloys keep both the ferromagnetic order and the metallic character. LSDA+U electronic structure calculations show that the tetragonal phase is characterized by the 4f localized electrons of the rare earth element Eu from where originates the magnetism, and by their 3d-Fe electrons responsible for superconductivity. The substitution of As by P leads to a decrease in the volume and to a slight influence of magnetism of the Eu sublattice. LSDA+U calculations reproduce successfully the observed experimental findings. Finally, we provide indications on the coexistence of superconductivity and magnetism for few concentrations.