Investigation of Energy Band Structure and Physical Properties of 45 Electron System

1.通过对Ce-La-Ni化合物晶格常数的测定，认为Ce原子的离子态为+3.3.2。采用提拉法生长了CeNi单晶，并观察到dHvA效应.发现CeNi化合物具有致密的近藤效应.在<l-x>静水压力下，用感应法测量了Tb（Al_ CO_x）_2，0 &lt; x &lt; 0.1铁磁居里温度的压力效应。这些化合物的居里温度随压力的增加而增加，而dTc/dp随钴浓度的变化与Gd（A1_Co_2）_2.5相比变化不大<l-x>。用绝热法测量了ErNi、GdNi和HoNi铁磁化合物在2.2-100 K温度范围内的比热。这些样品的比热表现出与磁序相对应的异常。结果表明，CeNiSn是一种致密的近藤化合物，其电子比热系数为223 mJ/mol。K2高于5.4K.7。发现CeNiAl_4是一个新的致密近藤化合物，在1.6K以上是非磁性的。Pr和Nd Heusler化合物具有较大的负顺磁居里温度，分别为-19K和-29K。

1. From the measurement of lattice constant of Ce-La-Ni compounds, it was considered that the ionix state of Ce atom is +3.3.2. Single crystal of CeNi was grown by the Czochralski pulling method and dHvA effect was observed.3. It was found the CeNi compound shows the dense Kondo effect.4. The pressure effect of the ferromagnetic Curie temperature in Tb (A1_<l-x>CO_x)_2, 0 < x < 0.1 was measured by the induction method under hydrostatic pressure. The Curie temperatures of theses compounds increased with increasing pressure and the derivative dTc/dp as a function of cobalt concentration did not change so much compared with that of Gd (A1_<l-x>Co_2)_2.5. The specific heats of the ferromagnetic compounds ErNi, GdNi, and HoNi were measured by means of the adiabatic method in the temperature range 2.2-100 K. The specific heats for these samples showed anomalies corresponding to the magnetic orders.6. It is found that CeNiSn is a dense Kondo compound with an electronic specific heat coefficient 223mJ/mol. K2 above 5.4K.7. It is found that CeNiAl_4 is a new member of the dense-Kondo compounds in the valencefluctuation regime and that CeNiAl_4 is non-magnetic above 1.6K.8. Pr and Nd Heusler compounds have large negative paramagnetic Curie temperatures -19K and -29K, respectively.