Synthesis, structure and physical properties of the new layered oxyselenides Bi₂LnO₄Cu₂Se₂ (Ln = rare earth)

We have synthesized a new series of layered oxyselenides Bi₂LnO₄Cu₂Se₂ (Ln=Nd, Sm, Eu, Dy, Er, Yb). Their crystal structures and physical properties were studied through X-ray diffraction, electric transport measurements, bulk magnetization and first-principle calculation. All these compounds have a tetragonal structure with space group I4/mmm. They exhibit hole-type metallic behaviours which is also verified by the DFT calculation. The new Bi₂LnO₄-type block in these compounds may give people some enlightenment in synthesizing new iron-based superconductors or other layered compounds.