Magnetic relaxation phenomena in the superspin-glass system [Co₈₀Fe₂₀/Al₂O₃]₁₀

Authors

Sarbeswar Sahoo, Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, GermanyFollow
O. Petracic, Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, Germany
Christian Binek, University of Nebraska-LincolnFollow
Wolfgang Kleemann, Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg, GermanyFollow
J. B. Sousa, IFIMUP, Departamento de Fisica, Universidade de Porto, 4169-007 Porto, Portugal
Susana Cardoso de Freitas, INESC, Rua Alves Redol 9-1, 1000 Lisbon, PortugalFollow
P. P. Freitas, INESC, Rua Alves Redol 9-1, 1000 Lisbon, Portugal

Date of this Version

11-1-2002

Comments

Published in Journal of Physics: Condensed Matter 14 (2002), pp. 6729–6736. Copyright © 2002 Institute of Physics Publishing Ltd. Online at stacks.iop.org/JPhysCM/14/6729 Used by permission.

Abstract

Relaxation and temperature cycles of thermoremanent magnetization, M^TRM, in the superspin-glass phase of [Co₈₀Fe₂₀ (0.9 nm)/Al₂O₃ (3 nm)] ₁₀ have been investigated. The relaxation of M^TRM exhibits ageing phenomena. In negative temperature cycles for temperature steps larger than 1 K the magnetic state is retrieved (memory effect) on returning to the measurement temperature. This property is independent of the application of a field step during intermediate cooling. In positive temperature cycles the relaxation is suppressed after temporary heating. The observations are discussed in the light of both the droplet and the hierarchical picture.