https://doi.org/10.1140/epjb/e2008-00445-9
Complex magnetic internal order in structurally disordered Ni nanoparticles
1
Instituto de Física Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), CP, 6165 Campinas, SP, Brazil
2
Centro Atoìmico Bariloche (CAB), CP 8400 S.C. de Bariloche, RN, Argentina
3
Laboratório Nacional de Luz Síncrotron (LNLS), 13084-971 Campinas, SP, Brazil
Corresponding author: a debiasi@cab.cnea.gov.ar
Received:
6
August
2008
Revised:
22
October
2008
Published online:
9
December
2008
A detailed study of the magnetic properties of colloidal Ni nanoparticles (∼5.2 nm) that do not present long range order is presented. Two magnetic contributions were observed at high temperatures (>25 K), a dominating paramagnetic one and a ferromagnetic contribution, detected by ferromagnetic resonance and low field magnetic measurements. Interestingly, the ferromagnetic behavior does not follow a classical superparamagnetic description. The effective anisotropy increases at low temperatures due to interactions among the ferromagnetic clusters, which leads the system to a frustrated state.
PACS: 75.75.+a – Magnetic properties of nanostructures / 75.50.Tt – Fine-particle systems; nanocrystalline materials / 75.50.Kj – Amorphous and quasicrystalline magnetic materials / 75.50.Lk – Spin glasses and other random magnets
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008