Remanent magnetization in CoO antiferromagnetic nanoparticles

• Main Author: Silva, N. J. O.
• Publication Date: 2010
• Other Authors: Millán, A., Palacio, F., Martins, M., Trindade, T., Puente-Orench, I., Campo, J.
• Format: Article
• Language: eng
• Source: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Download full: http://hdl.handle.net/10773/6298

We report a study on the remanent magnetization Mr induced by field cooling across the ordering temperature TN in antiferromagnetic CoO nanoparticles with different sizes. The nanoparticles are composed by a structurally and magnetically ordered core and a structurally ordered and magnetically disordered shell with a thickness of about 2 nm. The ordered core has cell parameters, moments direction, and modulus similar to those of bulk CoO. Mr is shown to be proportional to the cooling field Hcool. The low-temperature saturation values of Mr Mr 0 in the CoO nanoparticles are about two orders of magnitude higher than those found for bulk CoO. Mr /Mr 0 of CoO nanoparticles scales with temperature in a single curve, independently on the magnitude of Hcool and on nanoparticles size, except for temperatures near to TN since TN is size dependent.