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Title: Inter-grain interaction in random magnetic anisotropy simulation in magnetic nanocrystals

Effect of inter-grain exchange interaction on the coercive forces was analyzed with a numerical simulation in magnetic materials with random magnetic anisotropy. The magnetization of an assembly of magnetically interacting grains with randomly oriented uniaxial anisotropy was calculated using the Landau-Lifshitz-Gilbert equation. We supposed a single spin model where the magnetizations in a grain were aligned in the same direction, for simplicity. Calculations were carried out for an N×N×N system, where the number of grains on a side, N ranged from 16 to 128. The relation between the coercive forces H{sub C} and the grain size D is represented by H{sub C}∝D{sup k}. With the increase of N, k decreased gradually and tended to reach a saturated value around k = 4.5–5, which dose not correspond to the primitive theory of the random anisotropy model where k = 6. The deviation was discussed in terms of the inter-grain interaction, essentially proportional to the inverse of D.
Authors:
; ;  [1] ; ;  [2] ;  [3]
  1. Institute of Applied Physics, University of Tsukuba, Ibaraki 305-8573 (Japan)
  2. High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan)
  3. National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan)
Publication Date:
OSTI Identifier:
22403025
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; ANISOTROPY; COERCIVE FORCE; COMPUTERIZED SIMULATION; DIFFERENTIAL EQUATIONS; EXCHANGE INTERACTIONS; GRAIN SIZE; MAGNETIC MATERIALS; MAGNETIZATION; NANOSTRUCTURES; RANDOMNESS; SPIN