Hydrostatic high-pressure studies on the ferromagnetic Kondo-lattice compounds CePdSb and CeAg to 16 GPa

The dependence of the Curie temperature Tc of the ferromagnets CeAg and CePdSb on hydrostatic pressure P to 3.2 and 16 GPa, respectively, has been determined using a diamond-anvil cell loaded with dense helium as pressure medium. For both compounds, Tc(P) initially increases with applied pressure, followed by a maximum at approximately 1(10) GPa for CeAg(CePdSb). Above 3(15) GPa for CeAg(CePdSb), no ferromagnetic transition could be detected. The present results are compared with earlier studies and discussed within the framework of a phase diagram proposed by Doniach for Kondo lattice systems. CePdSb is the first cerium compound where the dependence of Tc on P unequivocally displays the asymmetric peak predicted by this phase diagram.