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

Document Type

Article

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.