LOW-TEMPERATURE THERMAL AND HIGH-PRESSURE STUDIES OF CEPD AND CEAGSB2

The anomalous properties of the Kondo lattice CeAgSb2 are compared wit h the well behaved Kondo system, CePd. The law-temperature thermal exp ansion of CePd is in agreement with previous heat capacity data, showi ng a ferromagnetic transition at T-c = 6.5 K and a second transition a t 3.5 K probably due to reorientation of the magnetic moments. The Gru neisen factor, calculated from thermal-expansion and heat capacity is gamma(G) approximate to 4.5, the same as the Gruneisen factor gamma(P) calculated from the pressure dependence and comparable to a previous measurement of gamma(P) approximate to 6. Thermal expansion measuremen ts (in fields of up to 8 T) and ac susceptibility measurements (under pressures of up to 7.33 kbar) have been made on CeAgSb2 in the tempera ture range 1.6-40 K. The zero-pressure ac susceptibility measurements confirm that there is an antiferromagnetic transition at T-N = 9.5 K, as previously reported. The magnetic contribution to the linear therma l-expansion coefficient of polycrystalline CeAgSb2 (alpha(p)) in zero magnetic field has a maximum value near 17 K and becomes small by 29 K . There is no peak in alpha(p) at the Neel temperature. The Neel tempe rature is found to decrease under pressure at the rate of partial deri vative(In T-N)/partial derivative P = -10.1 Mbar(-1), which indicates that CeAgSb2 is a magnetic Kondo lattice (with T-K > T-N) On the right -hand side of the Doniach diagram.