Interacting ferromagnetic nanoparticles in discontinuous Co₈₀Fe₂₀/Al₂O₃ multilayers: From superspin glass to reentrant superferromagnetism

Authors

W. Kleeman, Laboratorium fu¨r Angewandte Physik, Gerhard-Mercator-Universita¨t, D-47048 Duisburg, GermanyFollow
O. Petracic, Laboratorium fu¨r Angewandte Physik, Gerhard-Mercator-Universita¨t, Duisburg, Germany
Christian Binek, University of Nebraska-LincolnFollow
G.N. Kakazei, IFIMUP, Departamento de Fisica, Universidade de Porto, Porto, Portugal
Yu. G. Pogorelov, IFIMUP, Departamento de Fisica, Universidade de Porto, Porto, Portugal
J.B. Sousa, IFIMUP, Departamento de Fisica, Universidade de Porto, Porto, Portugal
Susana Cardoso de Freitas, INESC, Rua Alves Redol 9-1, Lisbon, PortugalFollow
P.P. Freitas, INESC, Rua Alves Redol 9-1, Lisbon, Portugal

Date of this Version

March 2001

Comments

Published by American Physical Society. Copyright 2001. Permission to use. Phys. Rev. B 63, 134423 (2001).

Abstract

Dipolar superferromagnetism with reentrant low-temperature superspin glass behavior is observed on a randomly distributed ferromagnetic nanoparticle systems in discontinuous metal-insulator multilayers [Co₈₀Fe₂₀/Al₂O₃ (3 nm)] ₁₀ with nominal thickness 1.1<~t<~1.3 nm by use of ac susceptometry and dc magnetometry. At t=1.0 nm, superspin glass-like freezing is evidenced by the criticality of dynamic and nonlinear susceptibilities.