Transition warming and cooling remanences in magnetite

摘要: [1] Insight into the size and morphology of assemblages magnetite particles can be gained by comparing temperature variations remanence or susceptibility after zero-field cooling (ZFC) field (FC) through Verwey transition around Tv = 120 K. At 10 K a sample is demagnetized following ZFC, but in FC initial state before warming has (TrCRM) acquired crossing Tv. The matching (TrWRM) as result heating from low across often called inverse thermoremanent magnetization (ITRM). In TrCRM experiments, initially samples were cooled 2 mT 300 to Magnetization M was measured at 1 5 intervals, highest-resolution data being taken between 140 90 zeroed K, monitored during back properties TrCRMs are generally similar those TrWRMs produced ZFC 12 (grain sizes 0.6 135 μm), monoclinic exactly equals cubic Tv, even though ultimate TrWRM values when H → 0 entirely different. Mirror-image symmetry observed in-field curves tracking acquisition symmetry, with increases field-on mirroring decreases field-off Mr curves, almost perfect 110 Approximate also production Detailed study mechanism(s) remanences will help clarify why ZFC/FC method diagnostic some instances not others.