OBSERVATION OF 4D FERROMAGNETISM IN FREESTANDING PD FINE PARTICLES

We report on observation of 4d ferromagnetic ordering in pure Pd fine particles. Results of our dc magnetic measurements as a function of Pd particle size show that the magnetization increases rapidly with decr easing particle size; a sample with 59 Angstrom median radius at 1.8 K under 4 kOe shows a factor of nineteen larger magnetization than that of Pd bulk. We suggest that only the surface monolayers of Pd particl es are magnetic. The ferromagnetic moment we deduced based on this ass umption is 0.23 +/- 0.19 mu(B) per atom which is comparable to the val ue predicted by the ab initio calculation.