Premium
More on the low‐temperature magnetism of stable single domain magnetite: Reversibility and non‐stoichiometry
Author(s) -
CarterStiglitz Brian,
Moskowitz Bruce,
Jackson Michael
Publication year - 2004
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 - 10.1029/2003gl019155
Subject(s) - remanence , magnetocrystalline anisotropy , magnetite , materials science , stoner–wohlfarth model , single domain , stoichiometry , magnetism , rock magnetism , magnetization , magnetic anisotropy , condensed matter physics , magnetic field , chemistry , physics , metallurgy , quantum mechanics
The loss in remanence at the Verwey transition (T V ) 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 zero‐field 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 T V and increases the “delta ratio” (δ fc /δ zfc ) 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.