Open AccessThe acquisition of thermoremanent magnetization by multidomain single‐crystal titanomagnetite
Author(s) -
Tucker P.,
O'Reilly W.
Publication year - 1980
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1980.tb02578.x
Subject(s) - thermoremanent magnetization , coercivity , remanence , condensed matter physics , demagnetizing field , materials science , magnetization , hysteresis , field (mathematics) , isothermal process , field dependence , dislocation , mineralogy , magnetic field , geology , physics , thermodynamics , mathematics , quantum mechanics , pure mathematics
Summary. Large, well‐characterized single‐crystals of titanomagnetite of approximate composition Fe 2.4 Ti 0.6 O 4 were ground into spheres and orientated along specific crystallographic axes. The field dependences of the thermoremanent magnetization (TRM) and the temperature dependences of the magnetic hysteresis properties were measured and evaluated against the available theoretical models. The models, of necessity simplifications of real materials, were unable to account for many features of the experimental curves. The discrepancies were partly resolved by consideration of the mode of blocking of each individual coercivity fraction. It was deduced that the domain‐walls were pinned by both dislocation lines and by inclusions or voids. A fraction of the walls were not thermally blocked. They could however be thought of as being blocked isothermally as the applied field was relaxed. The proportion of remanence blocked in by each process was found to be dependent on the strength of the inducing field through the field dependence of the blocking temperatures. A simplified model, taking these effects into account, was developed. This predicts the main features of the TRM acquisition curve and of the alternating field and thermal demagnetization spectra.