《Studies on magnetic aftereffect of Fe3O4 nano-particles》.pdf

Journal of Alloys and Compounds 429 (2007) 40–45 Studies on magnetic aftereffect of Fe O nano-particles 3 4 Deng-lu Hou a,∗, Zi-xia Du a , Cai-xia Yue a , Qing-hua Liub a Department of Physics, Hebei Normal University, Shijiazhuang 050016, China b Department of Physics, Xingtai University, Xingtai 054001, China Received 7 March 2006; received in revised form 2 April 2006; accepted 5 April 2006 Available online 24 May 2006 Abstract The magnetic aftereffects of Fe3 O4 nano-particles were simulated by Preisach hysteresis model, the results showed excellent agreement with the experiment data. The simulating results showed that due to the wide distribution of interaction field, magnetization decay followed typical logarithmic time dependence, and the decay occurred more rapidly for field closer to the coercivity. The thermal fluctuation field and activation volume were also obtained, which are the main characteristics of the thermal fluctuations in magnetic recording medium. From the fact that activation volume is larger than the mean particle size, we deduced the reversal magnetization mechanism. One set of parameters used in simulating hysteresis loops and magnetic aftereffects has unified the hysteresis and magnetic aftereffect phenomena. The aftereffects under double-field were calculated, and the condition under which the time dependence of magnetization was non-monotonic was given. © 2006 Elsevier B.V. All rights reserved. Keywords: Preisach model; Magnetic aftereffect; Fluctuation field; Activation volume 1.