2006/08/13 by Masatsugu Suzuki, Suzuki, Masatsugu, Sharbani I. Fullem +8
Engineering · Materials Science · Physics and Astronomy · #Characterization and Applications of Magnetic Nanoparticles #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Magnetic Properties and Applications #Theoretical and Computational Physics #cond-mat.dis-nn
paper · pdf · doi:10.48550/arxiv.cond-mat/0608297
7 pages, 7 figures
openalex publication_date 2006/08/13 · arxiv created 2008/11/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The aging and memory effects of Fe3O4 nanoparticles have been studied using a series of zero-field cooled (ZFC) and field-cooled (FC) magnetization measurements at various aging protocols. The genuine ZFC magnetization after the ZFC procedure with a single stop and wait process shows an aging dip at the stop temperature on reheating. The depth of the aging dip is dependent on the wait time. The frequency dependence of the AC magnetic susceptibility is indicative of critical slowing down at a freezing temperature Tf (= 30.6 ± 1.6 K). The relaxation time τ is described by a power law form with a dynamic critical exponent x (= 8.2 ± 1.0) and a microscopic relaxation time τ0 [=(1.33 ± 0.05) × 10-9 sec]. The ZFC-peak temperature decreases with increasing magnetic field (H), forming a critical line with an exponent p = 1.78 ± 0.26, close to the de Almeida-Thouless exponent (p = 3/2). These results indicate that the superspin glass phase occurs below Tf.