Presa Muñoz De Toro, Patricia Marcela De LaMultigner, M.Venta,, J. de laGarcía, M. A.Ruiz González, María Luisa2023-06-202023-06-202006-12-150021-897910.1063/1.2401314https://hdl.handle.net/20.500.14352/52152© 2006 American Institute of Physics. One of the authors (P.d.l.P.) gratefully acknowledges enlightening discussions with Professor P. Crespo and Professor J. M. González-Calbet on the subject of magnetism in gold nanoparticles. The continuous encouragement of Professor A. Hernando and his critical reading of the manuscript has been very helpful. Financial support from the Spanish MCyT under Project No. MAT2002–04246-c05–05 and CAM under Project No. S-0505/MAT/0194 are acknowledged.In this work the study of oleic acid and oleylamine-capped gold nanoparticles is presented. The structural characterization of the sample shows 6.7 nm gold nanoparticles with a narrow size distribution. The experimental optical absorption spectrum has a maximum at 2.35 eV. The calculated optical absorption spectrum is shifted and narrower than the experimental one, indicating that the oleic acid and oleylamine do not merely passivate the metallic nanoparticles but modify its electronic structure. These gold nanoparticles show in addition a kind of magnetic order similar to other organic passivated gold nanoparticles as thiol-capped gold nanoparticles. Although the magnetic interactions seem to be weaker than in thiol-capped ones, the magnetic behavior looks similar to that, i.e., an invariant temperature dependence of the magnetization from 5 to 300 K and a noticeable coercive field. We analyze the influence of the organic layer bonding the nanoparticles on the magnetic behavior.engjournal articlehttp://dx.doi.org/10.1063/1.2401314http://aip.scitation.orgopen access538.9Self-assembled monolayersNanocrystalsBiomedicineFísica de materialesFísica del estado sólido2211 Física del Estado Sólido