Influence of Pt substitution on magnetic properties of multipolar ordering compounds Ce(Pd,Pt)^sub 3^S^sub 4

We have studied the magnetic properties of the multipolar ordering compounds Ce (Pd1-xPtx)3S4 with 0.00 ≤x≤ 0.53 by means of magnetic susceptibility and magnetization measurements. In Ce Pd3S4, a simultaneous phase transition of the antiferro quadrupolar (AFQ) ordering and ferro magnetic (FM) ordering has been observed at 6.3 K. It has been suggested that the primary order parameter of CePd3S4 is the quadrupole moments, and it has not been understood why the FM ordering occurs at very high temperature which is almost the same magnetic transition temperature of GdPd3S4. GdPd3S4 shows an antiferromagnetic (AFM) transition at 5.8 K. With increasing Pt substitution in CePd3S4, the FM transition temperature TC(x) is rapidly suppressed to 2.4 K for x ≃ 0.3 and approaches asymptotically to 1.9 K(x=0.53). The results of magnetization curve suggest that the ordered state below TC (x) remains FM and AFQ ordered state for the whole range of x. For x ≥ 0.29, TC(x) reaches at around 2 K, a new AFM transition was observed at TN(x) ≃ 7 K. We determined the T - x phase diagram, and discuss the phase transitions at TC(x) and TN(x). The results suggest the possibility of the presence of the correlation between the magnetic interaction and the quadrupole interaction, and the correlation is not understood based on the previous multipolar model.