MAGNETIC, THERMAL AND TRANSPORT-PROPERTIES OF CENIGA2

We have measured the electrical resistivity rho, thermoelectric power S, Hall coefficient R(H), magnetic susceptibility chi, magnetization M and specific heat C of CeNiGa2 and LaNiGa2 polycrystalline samples. For CeNiGa2, an antiferromagnetic (AF) transition was found at T-N=4 K. The gamma value of 490 mJ/K-2 mol at T much less than T-N indicates the enhanced electron mass even in the AF state. At the same temperature region, rho shows a T-2 dependence, the coefficient of which follows the Kadowaki-Woods plot. From C(T), it is found that the first excited doublet is lying at similar to 30 K and the Kondo temperature has the same order. The observed broad peaks in rho at 20 K and S at 12 K are explained by the combination of the crystal field and the Kondo effect. LaNiGa2 shows a bulk superconductivity with the transition temperature of 2.0 K.