<研究ノート>¹⁹⁵Pt-NMR による白金ナノ粒子における量子サイズ効果の表面効果との分離及び異常な磁気揺らぎの検出

Abstract

Nanoparticles systems are important in both application and fundamental studies. In 1962, the theory of nanoparticles was formulated and predicted that the discrete energy levels in nanoparticles were realized and that the physical quantities behave differently from that of bulk at low temperatures where the thermal fluctuations fall below the energy spacing of the discrete energy levels. In addition, the behavior of physical quantities depends on the parity of the number of the electrons in a nanoparticle. This is termed quantum size effects (QSEs). Although, to date, various studies on nanoparticles have been conducted, the QSEs were not well separated from surface effects, which originate from the difference between surface and interior regions of nanoparticles. We succeeded in the separation of the QSEs and the surface effects, and found novel magnetic fluctuations related to the QSEs in Pt nanoparticles. The magnetic fluctuations at low temperatures are due to neither surface effects nor magnetic order, and their energy scale seems to be independent of electronic correlation. Further studies on such magnetic fluctuations have now proceeded.