Volume 108, Number 1, October 2014
|Number of page(s)||5|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||29 September 2014|
Ageing dynamics of a superspin glass
1 Department of Engineering Sciences, Uppsala University - Box 534, SE-751 21 Uppsala, Sweden
2 Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Física Aplicada, Universidad de Castilla-La Mancha - 13071 Ciudad Real, Spain
3 Institute of Bioengineering and Nanotechnology - 31 Biopolis Way, The Nanos, Singapore 138669, Singapore
Received: 27 June 2014
Accepted: 6 September 2014
Magnetization dynamics of a model superspin glass system consisting of nearly monodispersed close-packed maghemite particles of diameter 8 nm is investigated. The observed non-equilibrium features of the dynamics are qualitatively similar to those of atomic spin glass systems. The intrinsic relaxation function, as observed in zero-field–cooled magnetization relaxation experiments, depends on the time the sample has been kept at constant temperature (ageing). Accompanying low-field experiments show that the archetypal spin glass characteristics —ageing, memory and rejuvenation— are reproduced in this dense system of dipolar-dipolar interacting superspins.
PACS: 75.50.Tt – Fine-particle systems; nanocrystalline materials / 75.50.Lk – Spin glasses and other random magnets / 75.75.-c – Magnetic properties of nanostructures
© EPLA, 2014
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