28 June 2005 Magnetism and magneto-optics of Co nanoparticles embedded in dielectric and metallic matrices
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We present a structural, magnetic and magneto-optical (MO) study of Co nanoparticles sputter-deposited at different temperatures and embedded in three different matrices (two insulators such as MgO and AlN and a metal such as Pt). MgO capping layer does not affect the magnetism of the nanoparticles as demonstrated by in situ transversal and ex situ polar Kerr loops. The structure of the nanoparticles was investigated by TEM and a Co crystalline core surrounded by an amorphous crust was observed. From the analysis of the MO spectral response of the nanoparticles we demonstrate that the evolution of the MO constants as a function of Co concentration can be explained with the Maxwell-Garnett model. It is also observed that the reduction of nanoparticles size gives rise to a decrease of the relaxation time of the electrons into them. The deposition of Pt capping gives rise to the magnetic connection of the islands mediated by the polarised Pt, with the formation of different Co-Pt compounds as was observed with TEM. We observe that in the case of AlN capping destroys the magnetism of the samples due to a strong nitridation of Co.
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C. Clavero, A. Cebollada, G. Armelles, Y. Huttel, J. Arbiol, F. Peiro, A. Cornet, A. Llobera, C. Dominguez, "Magnetism and magneto-optics of Co nanoparticles embedded in dielectric and metallic matrices", Proc. SPIE 5838, Nanotechnology II, (28 June 2005); doi: 10.1117/12.608234; https://doi.org/10.1117/12.608234

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