Авторы: Dunlop D.

2003 г.

Geophys.Res.Lett.

  Magnetites with sizes from 1 mm to 135 mm were cooled in zero field and their magnetizations M(T) measured continuously. M(T) changed reversibly in cooling from T0 = 300 K to 200 K, and in subsidiary warming-cooling cycles Ti ! T0 ! Ti for any Ti. Changes in M(T) in cooling from 200 K to 130 K were largely irreversible due to decreasing magnetocrystalline anisotropy which promotes wall unpinning and domain nucleation. Low-temperature demagnetization (LTD) is almost complete by 130 K in 20–135 mm magnetites but in 1–14 mm magnetites further LTD occurs on cooling to 120 K as magnetocrystalline easy axes change and domains reorganize at the Verwey transition.

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