Ucu_(4+x)Al_(8-x) and its derivatives

摘要

The Ucu_5Tal_6 compound exist for T = Cr, Mn and Fe. The magnetic, electrical and thermodynamic properties have been examined in the temperature ranges 1.9-400 K, 4.2-300 K and 1.2-70 K, respectively. The temperature dependence of the magnetic susceptibility and the magnetization have been measured in the magnetic flux density of 5 kOe for all compounds and for the Mn alloy additionally in 1 kOe. The magnetization versus magnetic flux density has been determined in- magnetic flux density up to 50 kOe at 1.9 K, whereas for the Mn alloy the measurements have been extended to the temperature of 125 K and additionally in magnetic flux density up to 140 kOe at temperature of 4.2 K. The Cr alloy is paramagnetic whereas the Mn and Fe compound exhibit a ferromagnetic character below Tq amounting to 373 and 163 K, respectively. The magnetic susceptibility of the Cr and Fe compound follows the modified Curie-Weiss law. The electrical resistivity increases when temperature decreases, however, the absolute values correspond to metallic character. The thermoelectric power vs. temperature plot for the Fe alloy exhibits an anomaly which is related most probably to the Curie point. The coefficients of the electronic specific heat are enhanced suggested as the result of strongly correlated /-electrons or crystallographic disorder.