|Series||Geological Survey of Canada Bulletin -- 372|
A higher coercivity component, probably hematite, is also sometimes present. Interpretation and discussion The A component is probably a recently ac- quired secondary magnetization because of its low coercivity and low unblocking temperatures, combined with its post-tectonic age and similarity to the present Earth's magnetic field by: ARM is that remanence acquired when a sample is subjected to a decreasing alternating magnetic field in the presence of a small steady magnetic field (see Table ). The alternating field must initially be of sufficient strength to be able to saturate the magnetic grains in the sample. The remanence coercivity of maghemite (and magnetite) is 1 to 2 orders of magnitude less than that of hematite. The maghemite-to-hematite transition at about °C will be accompanied by a change in remanence coercivity. The measurements of H cr can be carried out after each heating step with an alternating force gradient magnetometer (μMAG) but the measurement procedure is considerably . Reliability of paleointensity methods using alternating field demagnetization and anhysteretic remanence. Using natural volcanic rocks which acquired thermoremanence (TRM) in known fields, reliability of various palaeointensity methods using alternating field (AF Author: Masaru Kono.
Changes in remanence, coercivity and domain state at low temperature in magnetite Oº zden Oº zdemira;*, David J. Dunlopa, Bruce M. Moskowitzb a Department of Physics, University of Toronto at Mississauga, Mississauga, ON, Canada L5L 1C6 b Institute for Rock Magnetism, University of Minnesota, Minneapolis, MN , USA Received 17 July ; received in revised form 18 October ; . The samples were crushed to a fine sand grain size and the k–T was measured at each 3 °C interval. The coercivity spectrum analysis (Dunlop, ) was performed by placing a specimen in a steady magnetic field that was progressively increased. Chemical remanent magnetization is produced by an increase in grain volume at temperatures below the blocking temperature of the grain. The process is analogous to TRM acquisition but in the case of CRM the relaxation time [see Eq. Remanence and Coercivity Remnance (or remanence or residual magnetism also residual magnetization) Sometimes the term retentivity is used for remanence. Remanence and Coercivity Remanence or remanent magnetization is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed.
Both processes affect the fidelity of the sediments as a recorder of the ancient field direction and relative paleointensity. In the present study, we report a rock magnetic study of three sedimentary cores of the late Pleistocene Lisan formation from Lake Kinneret (Sea of Cited by: N2 - This work reports on advanced remanence and coercivity measurements undertaken on a set of perpendicular exchange-coupled composite (ECC) media, where the demagnetizing field, H-D, has been properly accounted for. We find that, on correction, the shape of the hysteresis loop, and hence the shape of the remanence curve, changes significantly. The coercive force spectrum of magnetite at high temperatures: Evidence for thermal activation below the blocking temperature. Thermal activation of magnetization is the mechanism proposed by Néel to explain TRM (thermoremanent magnetization) and VRM (viscous remanent magnetization). A cautionary tale for palaeomagnetists: A spurious apparent single component remanence due to overlap of blocking-temperature spectra of two components.