Magnetic states and electronic properties of Sr4V2O6Fe2As2 studied by DFT calculations

摘要

In this work, we examine the magnetic stability of two incommensurate antiferromagnetic configurations and electronic band structures properties of Sr4V2O6Fe2As2 using first-principle density-functional-theory method. We show that the lowest total energy takes place in an incommensurate antiferromagnetic phase with the ordering wave vector q = (0.125, 0.125, 0) and ordered magnetic moment of 1.25 mu(B)/V. Based on the total as well as partial density of states (DOS) data, it concludes that both Fe-3d and V-3d orbitals give a rise to DOS around Fermi level and lead to the occurrence of Van Hove singularity associated with electronic instability. A strong inter-band scattering in the incommensurate anti-ferromagnetic phases is proposed, since this behaviour is followed by a larger number of electronic bands crossing Fermi level as compared to those in nonmagnetic one. Electronic bands and Fermi surface data affirm multi-band structure superconductivity, where electron-like sheets of carriers with low Fermi velocities occur at the corner of the Brillouin zone and hole-like cylinders of carriers with high Fermi velocities situate around the Gamma - Z line. Most importantly, our calculations predict the presence of both vertical and horizontal nodal lines, which seem to be distinct from usual feature of Fe-based superconductors with sole horizontal nodal lines.