Evolution of 4f heavy fermion state from 5f heavy fermion state in U<SUB>1-x</SUB>Ce<SUB>x</SUB>Pd<SUB>2</SUB>Al<SUB>3</SUB> system

We report the effect of Ce substitution for U in the heavy-electron antiferromagnetic superconductor UPd2Al3. CePd2Al3 is an established non-superconducting heavy-electron system which undergoes antiferromagnetic ordering below 2.8 K. Thus studies on U1-xCexPd2Al3 system provide a unique opportunity to observe the evolution from a 4f heavy-electron state to a 5f heavy-electron state. We have measured the resistivity and magnetic susceptibility from 1.5 to 300 K and the heat capacity from 2 to 20 K for several U1-xCexPd2Al3 samples. Our studies show that the antiferromagnetic (AF) ordering temperature (TN) of U1-xCexPd2Al3 does not decrease monotonically from TN = 14 K for UPd2Al3 to TN = 2.8 K for CePd2Al3 but rather shows a local maximum of 5 K near x = 0.4