Dresden 2003 – scientific programme

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MA: Magnetismus

MA 6: Magnetische Partikel / Cluster

MA 6.13: Talk

Monday, March 24, 2003, 18:15–18:30, HSZ/04

Aging and Relaxation Behavior of Superferromagnetic Domain State — •Xi Chen¹, O. Sichelschmidt¹, O. Petracic¹, Ch. Binek¹, W. Kleemann¹, S Cardoso², and P. P. Freitas² — ¹Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg — ²INESC, Rua Alves Redol 9-1, 1000 Lisbon, Portugal

The magnetic relaxation of the superferromagnetic discontinuous magnetic multilayer [Co₈₀Fe₂₀(1.4 nm)/Al₂O₃(3 nm)]₁₀ is investigated by SQUID magnetometry. After cooling the sample in a field from 400 K to different measurement temperatures, the decay of the thermoremanent magnetic moment m^TRM is measured. Surprisingly, an intermediate increase of m^TRM is observed, hence, two competing relaxation behaviors have to be assumed. One is the relaxation of the superferromagnetic domains, and the other one is the post-alignment of the frozen thermal disorder of the superspins inside the domains. In addition, aging and memory effects are found revealing the non-equilibrium behavior of the superferromagnet.