Journal ArticleDOI
Domain states in fine particle magnetite and titanomagnetite
TLDR
In this article, a simple model of domain structure is used to determine the particle size, mineralogical, stress and temperature dependence of the LEM domain states available to fine particles of magnetite and titanomagnetite (TM56).Abstract:
The domain state (single domain versus multidomain) of fine magnetic particles has long been associated with their remanent and hysteresis properties. Both domain observations and micromagnetic theory indicate that a large number of local energy minimum (LEM) domain states are available to single domain and multidomain particles. Theoretical calculations based on a simple model of domain structure are made to determine the particle size, mineralogical, stress and temperature dependence of the LEM domain states available to fine particles of magnetite and titanomagnetite (TM56). The global (or absolute) energy minimum (AEM) domain state depends primarily on the balance between magnetostatic and exchange energies and shows only a weak temperature dependence. The range of local energy minima (LEM) domain states depends primarily on the anisotropy energies (magnetocrystalline and magnetoelastic) and is strongly temperature dependent. From the evolution of domain structure as a function of temperature and grain size implied from the domain state calculations, the relative stabilities of Thermoremanent Magnetization (TRM), grain growth Chemical Remanent Magnetization (CRM) and trans-domain Viscous Remanent Magnetization (VRM) are discussed. The magnetic behavior of an ensemble of fine particles will depend on the LEM states initially occupied by the particles.read more
Citations
More filters
Journal ArticleDOI
A model of multidomain thermoremanent magnetization incorporating temperature‐variable domain structure
TL;DR: In this paper, a random element is considered to be the variation of direction of the easy axis of magnetization throughout the grain due to local crystal defects, or stress effects due to the domains themselves.
Journal ArticleDOI
High‐temperature magnetostriction of magnetite and titanomagnetites
TL;DR: Magnetostriction of synthetic polycrystalline magnetite and titanium-rich titanomagnetites has been measured from 25°C to their Curie temperatures as discussed by the authors.
Journal ArticleDOI
Micromagnetic study of the influence of crystal defects on coercivity in magnetite
TL;DR: In this paper, a one-dimensional micromagnetic model is used to calculate the thermal dependence of microcoercivity produced by the unpinning of a domain wall (DW) from various types of defects in magnetite.
Book ChapterDOI
Magnetic properties of rocks and minerals
Richard J. Harrison,Rafal E. Dunin-Borkowski,Takeshi Kasama,E. T. Simpson,Joshua M. Feinberg +4 more
TL;DR: The current state of the art in the field of computational and experimental mineral physics, as applied to the study of magnetic minerals, can be found in this paper, where the authors present a review of recent developments in the use of macroscopic magnetic measurements for characterizing and quantifying the microscopic spectrum of coercivities and interaction fields present in rocks and minerals.
Journal ArticleDOI
Magnetic domain observations on magnetite and titanomaghemite grains (0.5–10 μm)
TL;DR: In this paper, the authors used the Bitter method to observe the magnetic domain structures of natural titanomaghemite grains and magnetite crystals that were grown in a glass ceramic matrix.
References
More filters
Book
Single Crystal Elastic Constants and Calculated Aggregate Properties. A Handbook
Gene Simmons,Herbert F. Wang +1 more
TL;DR: In this paper, the authors present data on the elastic properties of single crystals collected from the literature through mid-1970 and the elastic property of isotropic aggregates which are calculated according to the schemes of Voigt and Reuss for all materials, and Hashin and Shtrikman for materials with cubic symmetry.
Book
Physics of magnetism
TL;DR: Paleomagnetism is the study of the magnetic properties of rocks as discussed by the authors, and it is one of the most broadly applicable disciplines in geophysics, having uses in diverse fields such as geomagnetic, tectonics, paleoceanography, volcanology, paleontology, and sedimentology.
Book ChapterDOI
On the theory of the dispersion of magnetic permeability in ferromagnetic bodies
TL;DR: This chapter examines the distribution of magnetic moments in a ferromagnetic crystal and finds that if the crystal is placed in an external magnetic field, the boundaries between the layers begin to move so that the layers with magnetic moments parallel to the field become wider.
Journal ArticleDOI
Some theoretical aspects of rock-magnetism
TL;DR: In this paper, a brief theoretical study of the most typical magnetic properties of rocks is devoted to the magnetic viscosity due to thermal agitation in small grains and in larger ones.