Low-temperature thermal and high-pressure studies of CePd and

Abstract

The anomalous properties of the Kondo lattice are compared with the well behaved Kondo system, CePd. The low-temperature thermal expansion of CePd is in agreement with previous heat capacity data, showing a ferromagnetic transition at and a second transition at 3.5 K probably due to reorientation of the magnetic moments. The Grüneisen factor, calculated from thermal-expansion and heat capacity is , the same as the Grüneisen factor calculated from the pressure dependence and comparable to a previous measurement of . Thermal expansion measurements (in fields of up to 8 T) and ac susceptibility measurements (under pressures of up to 7.33 kbar) have been made on in the temperature range 1.6-40 K. The zero-pressure ac susceptibility measurements confirm that there is an antiferromagnetic transition at , as previously reported. The magnetic contribution to the linear thermal-expansion coefficient of polycrystalline in zero magnetic field has a maximum value near 17 K and becomes small by 29 K. There is no peak in at the Néel temperature. The Néel temperature is found to decrease under pressure at the rate of , which indicates that is a magnetic Kondo lattice (with ) on the right-hand side of the Doniach diagram.