Transport properties of intermetallic compounds YT4Al8 (T = Mn and Cu)

Measurements of the electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) on the rare earth ternary intermetallic YMn4Al8 has been performed in the temperature range 10–300 K to investigate the electronic structure and the possible existence of pseudogap. YMn4Al8, with linear chains of Mn atoms, is an itinerant electron magnet that has a narrow pseudogap in the spin excitation spectrum. For comparison, the nonmagnetic counterpart YCu4Al8 has also been studied. It is found that the replacement of Cu for Mn leads to a dramatic increase in the electrical conductivity, indicating an increased metallic nature of YCu4Al8. The evident difference in the magnitude of the Seebeck coefficient between YMn4Al8 and YCu4Al8 as well as the sign reversal of S(T) in YCu4Al8 suggest that the Fermi level in YMn4Al8 is located within a rapidly varying density of states (DOS)/pseudogap and a significant change in temperature dependent DOS is taking place. A detailed analysis of the thermal conductivity by separating lattice and electronic contribution and the comparison with the electrical resistivity indicates a more ordered and increased metallic state for YCu4Al8 than that of YMn4Al8.