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Published on: February 20, 2016
Fe impurities weaken the ferromagnetic behavior in Au nanoparticles
P Crespo1, M A García, E Fernández Pinel
1Instituto de Magnetismo Aplicado (RENFE-UCM-CSIC), PO Box 155, 28230 Las Rozas, Madrid, Spain.
Physical Review Letters
|December 13, 2006
Summary
Magnetic impurities significantly lower the ferromagnetic order temperature in gold glyconanoparticles (GNPs). This finding suggests that the observed ferromagnetism in gold nanoparticles is not due to magnetic impurities.
Area of Science:
- Nanotechnology
- Materials Science
- Condensed Matter Physics
Background:
- Thiol-capped gold glyconanoparticles (GNPs) exhibit unique ferromagnetic properties.
- The origin of this ferromagnetism, particularly the role of magnetic impurities, requires clarification.
Purpose of the Study:
- To investigate the impact of magnetic impurities on the ferromagnetic behavior of gold glyconanoparticles.
- To determine if magnetic impurities are responsible for the observed ferromagnetism in gold nanoparticles.
Main Methods:
- Synthesis of thiol-capped gold nanoparticles (Au NPs) and gold-iron alloy nanoparticles (AuFe GNPs).
- Experimental measurement of spontaneous magnetization and magnetic hysteresis as a function of temperature.
Main Results:
- Magnetic impurities (Fe) were found to reduce the ferromagnetic order temperature in AuFe GNPs.
- Spontaneous magnetization in AuFe GNPs decreased rapidly with temperature, unlike in Au NPs.
- Magnetic hysteresis disappeared below 300 K in AuFe GNPs, indicating a reduction in local anisotropy field.
Conclusions:
- The ferromagnetism observed in gold nanoparticles is likely intrinsic and not caused by magnetic impurities.
- Iron impurities disrupt the local anisotropy field, suppressing the ferromagnetic characteristics of gold glyconanoparticles.
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