The transfer of magnetic moment on Au in Au@Fe oxide Magneto-Plasmonic (MPs) heterostructures exhibiting core-shell and heterodimer morphologies has been investigated. MPs are multifunctional nanomaterials composed by two different moieties having plasmonic and magnetic properties, respectively. New properties in addition arise from the interplay between the two materials [1,2] such as: enhancement of the magneto-optical response, modification of the plasmonic dynamics and changes in the reversal of magnetisation. The mechanisms determining these new effects are at the moment poorly understood. In this work we present a detailed study of the magnetic and chemical properties of colloidal Au@iron oxide nano-heterostructures having both a range of core@shell morphologies, and dumbbell-like heterodimers with different dimensions. Our investigation was carried out by combining XMCD and XANES spectroscopies, X-Ray Diffraction and SQUID magnetometry for investigating structural, magnetic properties and possible spin and charge transfer between the two components of the heterostructure. We demonstrate for the first time that spin transfer is possible in these metal/oxide heterostructures: a magnetic moment on gold was observed in Au @Fe oxide nanoparticles with lateral sizes of ca. 10 nm and composed by a mixture of Fe_{3}O_{4} and FeO. In other heterostructures with different composition, size and morphology a spin polarization on Au was not detected, excluding that the outcome is simply due to proximity effects. Our results indicate that the spin polarization is driven by the chemical nature of the iron oxide interfacing the Au core domain. This constitutes a new mechanism of spin polarization transfer, which is in addition compatible with plasmonic nanostructures. This research was supported by Cariplo project 2010-0612 and by NANOMAGMA (NMP3 FP7-214107-2).
Spin polarization in Au-Fe oxide magneto-plasmonic heterostructures
2012-01-01
Abstract
The transfer of magnetic moment on Au in Au@Fe oxide Magneto-Plasmonic (MPs) heterostructures exhibiting core-shell and heterodimer morphologies has been investigated. MPs are multifunctional nanomaterials composed by two different moieties having plasmonic and magnetic properties, respectively. New properties in addition arise from the interplay between the two materials [1,2] such as: enhancement of the magneto-optical response, modification of the plasmonic dynamics and changes in the reversal of magnetisation. The mechanisms determining these new effects are at the moment poorly understood. In this work we present a detailed study of the magnetic and chemical properties of colloidal Au@iron oxide nano-heterostructures having both a range of core@shell morphologies, and dumbbell-like heterodimers with different dimensions. Our investigation was carried out by combining XMCD and XANES spectroscopies, X-Ray Diffraction and SQUID magnetometry for investigating structural, magnetic properties and possible spin and charge transfer between the two components of the heterostructure. We demonstrate for the first time that spin transfer is possible in these metal/oxide heterostructures: a magnetic moment on gold was observed in Au @Fe oxide nanoparticles with lateral sizes of ca. 10 nm and composed by a mixture of Fe_{3}O_{4} and FeO. In other heterostructures with different composition, size and morphology a spin polarization on Au was not detected, excluding that the outcome is simply due to proximity effects. Our results indicate that the spin polarization is driven by the chemical nature of the iron oxide interfacing the Au core domain. This constitutes a new mechanism of spin polarization transfer, which is in addition compatible with plasmonic nanostructures. This research was supported by Cariplo project 2010-0612 and by NANOMAGMA (NMP3 FP7-214107-2).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
