Models of Maghematization: Observational Evidence in Support of a Magnetic Unstable Zone

Recent micromagnetic simulations predict that particles have an abnormal region of low magnetic stability for grain sizes near the domain state transitions from single to vortex. The implications this zone are not yet fully understood, but if size range window changes as a function applied field and temperature then it is likely contribute observational uncertainties in paleomagnetic recordings. narrow means its effects difficult identify when integrated across much wider distribution present sample. Here we report method examining unstable using oxidation magnetite. rock experiments on partially oxidized with median diameter close reinterpreted multilayer core-shell structure. predicted properties exhibit significantly improved agreement experimental data than previously reported coupled geometry. observed remanence coercivity associated structure proposed (∼80–∼120 nm), so provide first indication existence such region. We also demonstrate outside were stable maghemitization. research provides ideas study “magnetic zone” significant correct interpretation Finally, magnetite able record signals.