Interplay between 3d and 4f magnetism in CeCoPO

The ground state properties of CeCoPO, a homologue of the new high temperature superconductors LnFePnO1-xFx, were studied by means of susceptibility, specific heat, and resistivity measurements on polycrystals. The observation of a well defined Curie-Weiss behavior above 230 K with μeff=2.9μB and a ferromagnetic ordering below TC=75K is similar to what was observed in LaCoPO and points to magnetism of the Co-3d electrons. However, the Ce-ions are on the border to magnetism with a Kondo scale of TK~40K and show an enhanced Sommerfeld coefficient of γ~200mJ/molK2.