Potential parent compound of superconductor: Sr 2CuM 2As 2O 2 (M = Mn, Fe)

Abstract

The electronic structure of Sr 2CuMn 2As 2O 2 and Sr 2CuFe 2As 2O 2 are studied by the first-principle calculations. These compounds have a body-centered-tetragonal crystal structure that consists of the CuO 2 layers similar to those in the high- T c cuprate superconductor, and intermetallic MAs (M = Mn, or Fe) layers similar to the FeAs layers in high- T c pnictides. Such special structure makes them as interesting candidates for new type of superconductor since they have two types of superconducting layers. However, our calculations indicate that the states in the range from −2.0 eV to +2.0 eV are dominated by Mn-3d or Fe-3d states, while the states of Cu-3d are far away from the Fermi level (in the range from −3.0 eV to −1.0 eV). Such results are significantly different with the Cu-based superconductor, like La 2CuO 4, where the states around Fermi level are dominated by Cu-3d states. Besides, we find that the mean-field magnetic ground state is the checkerboard antiferromagnetic in Cu sublattice and the stripe antiferromagnetic in Fe (or Mn) sublattice.