TY - JOUR
T1 - More on the low-temperature magnetism of stable single domain magnetite
T2 - Reversibility and non-stoichiometry
AU - Carter-Stiglitz, Brian
AU - Moskowitz, Bruce
AU - Jackson, Michael
PY - 2004/3/28
Y1 - 2004/3/28
N2 - The loss in remanence at the Verwey transition (Tv) was modeled for elongate stable single domain magnetite for two experiments: 1) thermal cycling of room temperature saturation isothermal remanent magnetization (RTSIRM), 300 → 10 → 300 K, and 2) warming of zerofield cooled and field-cooled remanences from 10 K to 300 K. The RTSIRM simulations used magnetocrystalline anisotropy constants for stoichiometric magnetite and aspect ratios (AR) from 1 to ∞, for assemblages of inorganic particles and 10-magnetosome chains. The results match the experimentally observed behavior of reversibility. The second set of simulations was conducted with low-temperature magnetocrystalline anisotropy constants for varying degrees of non-stoichiometry, and AR = 5. Minor non-stoichiometry lowers the drop in remanence at Tv and increases the "delta ratio" (δfc/δzfc) to values as high as ∼6. New experiments demonstrate that maghematization (non-stoichiometry) can partly explain the low-temperature magnetic behavior observed in magnetotactic magnetite to date.
AB - The loss in remanence at the Verwey transition (Tv) was modeled for elongate stable single domain magnetite for two experiments: 1) thermal cycling of room temperature saturation isothermal remanent magnetization (RTSIRM), 300 → 10 → 300 K, and 2) warming of zerofield cooled and field-cooled remanences from 10 K to 300 K. The RTSIRM simulations used magnetocrystalline anisotropy constants for stoichiometric magnetite and aspect ratios (AR) from 1 to ∞, for assemblages of inorganic particles and 10-magnetosome chains. The results match the experimentally observed behavior of reversibility. The second set of simulations was conducted with low-temperature magnetocrystalline anisotropy constants for varying degrees of non-stoichiometry, and AR = 5. Minor non-stoichiometry lowers the drop in remanence at Tv and increases the "delta ratio" (δfc/δzfc) to values as high as ∼6. New experiments demonstrate that maghematization (non-stoichiometry) can partly explain the low-temperature magnetic behavior observed in magnetotactic magnetite to date.
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U2 - 10.1029/2003gl019155
DO - 10.1029/2003gl019155
M3 - Article
AN - SCOPUS:18544396049
SN - 0094-8276
VL - 31
SP - L06606 1-5
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 6
ER -