s-Electron ferromagnetism in gold and silver nanoclusters.

Luo, Weidong; Pennycook, Stephen J; Pantelides, Sokrates T · Nano Lett · 2007

basic_science · Level V

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Abstract

Ferromagnetic (FM) ordering in transition-metal systems (solids, surface layers, nanoparticles) arises from partially filled d shells. Thus, recent observations of FM Au nanoclusters was unexpected, and an explanation has remained elusive. Here we report first-principles density-functional spin-polarized calculations for Au and Ag nanoclusters. We find that the highest-occupied level is highly degenerate and partially filled by s electrons with spins aligned according to Hund's rule. The nanoclusters behave like "superatoms", with the spin-aligned electrons being itinerant on the outer shell of atoms.

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