Eur. Phys. J. B 74, 75-80 (2010)
https://doi.org/10.1140/epjb/e2010-00065-x

Role of anisotropy and interactions in magnetic nanoparticle systems

¹ Department of Physics and Astrophysics, University of Delhi, 110007 Delhi, India
² School of Sciences, Indira Gandhi National Open University, Maidangarhi, 110068 New Delhi, India
³ National Physical Laboratory, K. S. Krishnan Marg, 110012 New Delhi, India

Corresponding author: annapoorni@physics.du.ac.in

Received: 26 June 2009
Revised: 4 December 2009
Published online: 23 February 2010

Abstract

Magnetic nanoparticle systems are characterized by several competing effects like anisotropy, an inherent disorder, the long range dipolar and the short range exchange interactions due to clustering effects. The sensitivity of the observed static and dynamical properties of these systems like the blocking temperature, the hysteresis and the susceptibility, to the methods of preparation, annealing and the resulting morphology is a manifestation of this. However, given the complexity of the system, it is often difficult to isolate the effects which might be dominant in a particular sample, which has a direct bearing on the desired applications. In this paper we report the effects of anisotropy, interactions and particle concentration on the temperature dependent remanence and coercivity through a numerical simulation on an array of single domain magnetic particles which incorporates all the above mentioned factors. Our results show that it is possible to distinguish between purely anisotropic systems and interacting systems with these measurements. In confirmation of our simulation results we also present the experimental results on the remanence and coercivity of nanomagnetic nickel ferrite composites.