Resumen: The multilayer films Al2O3/tCo Co/tPt Pt]N, produced by sequential deposition of Co and Pt on alumina consist in layers of CoPt alloyed nanoparticles. They show perpendicular magnetic anisotropy (PMA) below a freezing temperature Tf, an asperomagnetic-like phase below that temperature, and hard ferromagnetic ordering below a transition temperature T1 < Tf. A single layer granular film (N = 1) with deposition thicknesses tCo=0.7 nm, tPt=1.5 nm and particle diameter of 3 nm is presently studied. SQUID magnetometry shows that a single layer presents the three phases as well. Para-, aspero-and ferromagnetic phases are observed upon lowering the temperature, with transition temperatures Tf ˜ 375 K and T1 ˜ 200 K, respectively. In addition, the PMA persists, proving that there is no interlayer coupling in the multilayer system. SQUID results also reveal a core-shell structure in the CoPt nanoparticles. Idioma: Inglés DOI: 10.4028/www.scientific.net/SSP.257.60 Año: 2017 Publicado en: SOLID STATE PHENOMENA 257 (2017), 60-63 ISSN: 1012-0394 Financiación: info:eu-repo/grantAgreement/ES/DGA/IMANA-E34 Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2014-53921-R Tipo y forma: Artículo (PostPrint) Área (Departamento): Área Cienc.Mater. Ingen.Metal. (Dpto. Ciencia Tecnol.Mater.Fl.) Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)