Superparamagnetism in Cobalt Nanoparticles Coated by Protective Gold Layer |
| P. Hrubovčáka, A. Zeleňákováa, V. Zeleňákb, J. Kováčc
aInstitute of Physics, Faculty of Sciences, P.J. Šafárik University, Park Angelinum 9, 041 54 Košice, Slovakia bDepartment of Inorganic Chemistry, Faculty of Sciences, P.J. Šafárik University, Moyzesova 11, 040 01 Košice, Slovakia cInstitute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice, Slovakia |
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| In this work we present the study on structural and magnetic properties of fine cobalt nanoparticles coated by protective gold layer synthetized by microemulsion method. Structural measurements (powder XRD, HRTEM) confirmed spherical shape of the particles, their nanocrystalline character and presence of individual Co and Au phases. Investigation of magnetic properties of the particles revealed superparamagnetic behavior at higher temperatures and magnetic hysteresis at low temperatures. Average magnetic moment of individual particle mp ~ 86.3μB was established. The critical temperature, below which the magnetic moments of the particles are blocked, was TB = 6 K. Investigation of magnetic relaxation processes via magnetic susceptibility, detected one maximum attributed to single relaxation process, present in the particles. Obtained data, interpreted in terms of Neél-Arrhenius and Vogel-Fulcher theoretical models, confirmed the presence of strong magnetic interparticle interactions. |
DOI: 10.12693/APhysPolA.126.216 PACS numbers: 75.40.Cx, 75.75.Fk, 68.37.Og |