Optical Properties in The Hole-Doped Ca8.5Na1.5(Pt3As8)(Fe2As2)5 Single Crystal

For newly synthesized hole-doped Ca8.5Na1.5(Pt3As8)(Fe2As2)5 single crystals, we measured the infrared reflectivity spectrum and the magnetic field dependence of magnetoresistivity and Hall resistivity. The results of these two experiments in normal states are well described by two band models. In the normal state below 150 K, the optical conductivity spectrum shows a transfer of spectral weights from the mid-infrared region to the near-infrared region. Meanwhile, the magnetoresistance and Hall resistance show a significant decrease in carrier density at 150 K. These two phenomena are due to the conversion of itinerant electrons to heavy electrons by the strong correlation effect, Hund's coupling. In the superconducting state, the spectral weight in the low frequency region by the superconducting condensate is completely suppressed, which is well analyzed by the generalized Mattis-Bardeen (M-B) model with a two superconducting gap.

Электронная структура интерметаллического соединения GdCuGe

The electronic structure of GdCuGe intermetallic compound has been studied. Spin-polarized energy spectrum calculations have been performed by the band method with allowance for strong electron correlations in the 4 f -shell of gadolinium ions. Antiferromagnetic ordering of GdCuGe at low temperatures has been obtained in a theoretical calculation, with the value of the effective magnetic moment of gadolinium ions reproduced in fair agreement with experimental data. The electronic density of states has been analyzed. An optical conductivity spectrum has been calculated for GdCuGe; it reveals specific features that are analogous to the ones discovered previously in the GdCuSi compound with a similar hexagonal structure.