Hysteresis and relaxation in granular permanent magnets

Journal Article · Sun Apr 01 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3672845· OSTI ID:1211301

Skomski, R; Balamurugan, B; George, TA; Chipara, M; Wei, XH; Shield, JE; Sellmyer, DJ

Some nontrivial aspects of the magnetic and structural characterization of hard-magnetic nanoparticles are investigated. Dilute ensembles are well-described by mean-field theory, although there is an asymmetry between exchange and magnetostatic interaction fields. Corrections to the mean-field approximation are caused by cooperative effects and have the character of Onsager reaction fields, which are much stronger in micromagnetism than in atomic-scale magnetism. The slow dynamics of zero-field-cooled (ZFC) magnetization curves is strongly affected by the particles' magnetic anisotropy, which reduces the corresponding energy-barrier height from 25 to 19.1 k(B)T. (C) 2012 American Institute of Physics. [doi:10.1063/1.3672845]

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• OSTI ID: 1211301
• Journal Information: Journal of Applied Physics, Vol. 111, Issue 7; ISSN 0021-8979
• Country of Publication: United States
• Language: English