Observations of Large Magnetic Moments in Icosahedral Pb Nanoparticles

Abstract

We report on the observation of a large magnetic moment in 7 nm icosahedral Pb particles. This moment is 140 times stronger than that developed in 6 nm fcc Pb particles. The saturation magnetization of 7 nm icosahedral Pb particles exhibits a peak at 40 K, which is reduced by only 9% when the temperature is increased from 40 to 300 K. No sign of the occurrence of superconductivity is observed in 7 nm icosahedral Pb particles upon cooling to 1.8 K, whereas superconductivity develops below 6.6 K in 6 nm fcc Pb particles. It is the icosahedral atomic arrangement that generates the large magnetic moment and suppresses the development of superconductivity in these nanoparticles.