Related Experiment Video
Updated: Jun 14, 2026
08:04
Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating
Published on: February 20, 2016
Coupling between magnetic and optical properties of stable Au-Fe solid solution nanoparticles.
C de Julián Fernández1, G Mattei, E Paz
1INSTM RU at the Department of Chemistry of the University of Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino, Italy. cesar.dejulian@unifi.it
Nanotechnology
|March 30, 2010
Summary
Ion-implanted gold-iron (Au-Fe) nanoparticles exhibit unique magnetic and optical properties due to electronic band hybridization, not just size effects. These multifunctional nanomaterials show promise for advanced applications.
Area of Science:
- Nanomaterials Science
- Solid-State Physics
- Magnetism and Optics
Background:
- Gold-iron (Au-Fe) nanoparticles are simple multifunctional nanomaterials with potential magnetic and optical properties.
- Bulk Au-Fe alloys are not stable in thermal equilibrium, necessitating non-equilibrium methods for nanostructure formation.
Purpose of the Study:
- To investigate and correlate the magnetic, optical, and magneto-optical properties of ion-implanted Au-Fe solid solution nanoparticles.
- To understand the influence of electronic band hybridization versus size effects on the properties of Au-Fe nanoparticles.
Main Methods:
- Fabrication of Au-Fe solid solution nanoparticles in a SiO(2) matrix via ion implantation.
- Characterization of optical properties, including surface plasmon resonance (SPR) damping.
- Measurement of magnetic properties using x-ray magnetic circular dichroism (XMCD) to determine magnetic polarization and coupling.
Main Results:
- Au-Fe nanoparticles exhibit damped SPR compared to pure Au and Au-rich nanoparticles, especially at equicomposition.
- Au atoms are magnetically polarized and ferromagnetically coupled with Fe atoms in all investigated nanoparticles.
- Au-Fe nanoparticles show enhanced chemical stability over Fe nanoparticles, but with reduced magnetic moment per Fe atom and lower ordering temperature, attributed to electronic band hybridization.
Conclusions:
- The properties of Au-Fe nanoparticles are significantly influenced by electronic band hybridization within the solid solution, rather than solely by size effects.
- The stabilization of the Au-Fe alloy is attributed to the out-of-equilibrium ion implantation process and size-dependent property changes.
- The observed magneto-optical transitions in the visible-near-infrared (vis-nIR) regions are similar across different compositions.
Related Concept Videos
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.