MAGNETIC AND ELECTRICAL-PROPERTIES OF UCU2GE2

Of the many interesting U and Ce compounds in the ThCr2Si2 structure UCU2Ge2 is unusual in showing the onset of ferromagnetism at a fairly high temperature (105 K) but its apparent replacement by antiferromagnetism at low temperatures. We have made detailed studies of the magnetic behaviour and electrical resistance in this compound and of the effects of Ce substitution for U and some examination of the effects of Si substitution for Ge. Ce lowers the Curie temperature and fairly rapidly raises the temperature at which antiferromagnetic components appear, and by 50% Ce substitution only antiferromagnetic order is found. Si substitutions for Ge have much less effect on UCu2Ge2.