Evidence of interface exchange magnetism in self-assembled cobalt-fullerene nanocomposites exposed to air

0477480 - ÚJF 2018 RIV GB eng J - Journal Article
Lavrentiev, Vasyl - Stupakov, Alexandr - Lavrentieva, Inna - Motylenko, M. - Barchuk, M. - Rafaja, D.
Evidence of interface exchange magnetism in self-assembled cobalt-fullerene nanocomposites exposed to air.
Nanotechnology. Roč. 28, č. 12 (2017), č. článku 125704. ISSN 0957-4484. E-ISSN 1361-6528
R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠMT LM2015056
Institutional support: RVO:68378271 ; RVO:61389005
Keywords : fullerene * cobalt clusters * cobalt oxide * nanocomposite * interface exchange magnetism
OECD category: Condensed matter physics (including formerly solid state physics, supercond.); Electrical and electronic engineering (FZU-D)
Impact factor: 3.404, year: 2017

We report on the establishing of an exclusive magnetic effect in. air-exposed CoxC60 nanocomposites (x > 2) created through self-assembling in the depositing mixture. In order to verify the influence of ambient air on the CoxC60 mixture film, we have studied in detail. the film magnetization at rather low temperatures, which provides their ferromagnetic behavior. Tracing the possible exchange bias effect, we distinguished a clear. vertical shift of the hysteresis loops recorded for the air-exposed CoxC60 films in the field cooling (FC) regime. The detected vertical shift of the FC loops is caused by an uncompensated magnetic moment M-u induced by exchange coupling of the Co spins at the Co/CoO interface. This interface arises due to the oxidation of small Co clusters distributed in a C-60-based matrix of self-assembled composite films, which occurs during air exposure. The core-shell structure of the Co/CoO magnetic clusters (about 2-3 nm in size) consisting of a epsilon-Co core and fcc-CoO shell was confirmed by means of transmission electron microscopy. Established interface magnetism testifies to a composite nanostructure in the CoxC60 mixture film with x > 2 and explains the influence of. air exposure on the film structure. The discovered magnetic effect implies a new application potential for cobalt-fullerene composites in sensors and catalysis.
Permanent Link: http://hdl.handle.net/11104/0273828