Observation of 4d ferromagnetism in free-standing Pd fine particles

¹ Department of Materials Science, Faculty of Science and Technology Keio University - Yokohama 223, Japan
² Department of Instrumentation Engineering, Faculty of Science and Technology, Keio University - Yokohama 223, Japan

Received: 2 September 1996
Accepted: 14 March 1997

Abstract

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 decreasing particle size; a sample with 59 Å 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 particles are magnetic. The ferromagnetic moment we deduced based on this assumption is per atom which is comparable to the value predicted by the ab initio calculation.