Magnetic properties of nano-particles of Au, Pd and Pd/Ni alloys

Well-characterized nanometer sized metal particles (nano-particle) with quite narrow diameter distribution have been synthesized by chemical method and their magnetic properties were investigated systematically using SQUID magnetometer and ESR spectrometer. Au and Pd nano-particles display the ferromagnetism contrary to the para- and diamagnetism in their bulk state. Moreover, the magnetization of Pd particles has been measured as a function of particle diameter and showed threshold size of about 3 nm. This result suggests the existence of a critical size changing from atomic to metallic spin correlation. (C) 2001 Elsevier Science B.V. All rights reserved.