Pressure dependence of magnetic order in CePd2Al2Ga

The Kondo lattice system CePd2Al3-CePd2Ga3 is distinguished by the observat ion of antiferromagnetism on the Al side and ferromagnetism on the Ga side, without a change in the crystal structure. At first sight, it appears as i f the influence of high pressure on both types of magnetic order in the ter nary compounds can be described in the usual picture of Doniach's phase dia gram. In CePd2Ga3 there is evidence for the breakdown of ferromagnetism und er pressure near 2.3 GPa, but there are also indications for the existence of a different type of magnetic order at higher pressure,just before the or der is completely suppressed. Here we have investigated the tetradic interm ediate compound CePd2Al2Ga which is closer to the antiferromagnetic side, b ut still is ferromagnetic (T-c = 1.8 K). The ordering temperature detected by AC-susceptibility shows a non-monotonic pressure dependence: after an in cipient rapid decrease below 0.1 GPa, it starts to increase again above 0.4 GPa. This behaviour is discussed and a tentative phase diagram is suggeste d. (C) 1999 Elsevier Science B.V. All rights reserved.