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A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions
Published on: February 5, 2016
s-Electron ferromagnetism in gold and silver nanoclusters
Weidong Luo1, Stephen J Pennycook, Sokrates T Pantelides
1Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA. wdluo@ornl.gov
Nano Letters
|September 18, 2007
Summary
Ferromagnetic ordering in gold nanoclusters was unexpected. Calculations reveal that aligned s electrons in a degenerate highest-occupied level create this magnetism, behaving like superatoms.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Ferromagnetic (FM) ordering typically arises from partially filled d shells in transition metals.
- Recent observations of FM behavior in gold (Au) nanoclusters are unexplained.
- Understanding the origin of magnetism in non-traditional FM materials is crucial.
Purpose of the Study:
- To investigate the underlying mechanism responsible for the observed ferromagnetic ordering in gold and silver nanoclusters.
- To provide a theoretical explanation for the unexpected magnetic properties of Au nanoclusters.
Main Methods:
- Utilized first-principles density-functional theory (DFT) calculations.
- Performed spin-polarized relativistic calculations.
- Investigated electronic structure and spin alignment in Au and Ag nanoclusters.
Main Results:
- Identified a highly degenerate highest-occupied electronic level in the nanoclusters.
- Found that s electrons partially fill this level and align their spins according to Hund's rule.
- Demonstrated that nanoclusters exhibit 'superatom' behavior with itinerant, spin-aligned electrons.
Conclusions:
- The observed ferromagnetic ordering in Au and Ag nanoclusters is attributed to the spin alignment of itinerant s electrons in a degenerate highest-occupied level.
- This 'superatom' electronic configuration explains the unexpected magnetism in these systems.
- The findings challenge traditional understanding of ferromagnetism in transition metals.
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