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Surface ferromagnetism of Pd fine particles
T Shinohara1, T Sato, T Taniyama
1Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-8522, Japan.
Physical Review Letters
|November 13, 2003
Summary
Gas-evaporated palladium (Pd) fine particles exhibit surface ferromagnetism. This magnetic ordering occurs on specific facets, involving the top atomic layers and contributing to unique magnetic properties.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Understanding the magnetic properties of noble metal nanoparticles is crucial for developing advanced magnetic materials.
- Previous studies on palladium nanoparticles have yielded mixed results regarding their magnetic behavior.
Purpose of the Study:
- To investigate the ferromagnetism of clean, gas-evaporated palladium (Pd) fine particles.
- To elucidate the relationship between particle size, surface structure, and magnetic properties.
Main Methods:
- Gas evaporation technique for synthesizing Pd fine particles.
- Surface characterization to ensure particle cleanliness.
- Magnetic property measurements, including size dependence of magnetic saturation.
Main Results:
- Clear evidence of ferromagnetism in clean Pd fine particles was observed.
- A magnetic heterostructure was identified, with a ferromagnetic surface and paramagnetic core.
- Ferromagnetic ordering was localized to (100) facets, involving the top 2-5 atomic layers.
- The magnetic moment per atom on the surface was determined to be (0.75 ± 0.31) μB/atom.
Conclusions:
- Clean Pd fine particles possess a unique magnetic heterostructure with a ferromagnetic surface.
- The ferromagnetism is facet-dependent and originates from the outermost atomic layers.
- These findings contribute to the understanding of surface magnetism in noble metal nanoparticles.