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Metastability threshold sizes in single‐domain magnetite particles
Author(s) -
Shcherbakov V. P.,
Lamash B. E.
Publication year - 1988
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl015i005p00526
Subject(s) - metastability , magnetite , single domain , materials science , condensed matter physics , grain size , particle size , particle (ecology) , domain (mathematical analysis) , single crystal , thermodynamics , physics , magnetic domain , mathematics , chemistry , geology , magnetic field , metallurgy , nuclear magnetic resonance , mathematical analysis , magnetization , quantum mechanics , oceanography
A micromagnetic model was developed to calculate the maximum grain size for which an ideal parallelepiped‐shaped particle can have a metastable single‐domain (SD) structure. For mathematical tractability, the micromagnetic equations were described only by one‐dimensional deviations from a uniform SD state. It was found that for cubic‐shaped magnetite particles, the metastability threshold, a cr was approximately 0.14 micrometers, well above the equilibrium threshold size for the single‐domain to two‐domain transition. The metastability threshold size also increased rapidly with particle elongation and for a length:width ratio greater then 2.6, magnetite grains of all sizes could theoretically support a metastable single‐domain state.