VOLUME EFFECTS ON THE MAGNETIC-PROPERTIES OF CUBIC ISOSTRUCTURAL INTERMETALLICS OF CE

We compare the magnetic behavior of CeAg, CeZn, and CeCd in the ferromagnetic phase under pressure, using total-energy electronic-structure calculations within the local-spin-density approximation. While the calculated magnetic moments at ambient pressure reflect the trend of the unit-cell volumes as the pressure is increased, an instability of the magnetic phase occurs in isovalent CeCd and CeZn at much lower applied pressure than in CeAg, as found by experiments. Results with use of a rigid-band model to fill in the density of states of CeAg with the same number of electrons as CeCd show that the different magnetic behavior of the two compounds is essentially due to a more effective screening of the complete 6s shell of Cd. Analogous conclusions are valid for CeZn; the calculated equilibrium volume of the ferromagnetic phase of CeZn is found within the experimental pressure range in which the observed order-order magnetic phase transition takes place.