Observing thermomagnetic stability of nonideal magnetite particles: Good paleomagnetic recorders?
Observing thermomagnetic stability of nonideal magnetite particles: Good paleomagnetic recorders?
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DOI：
10.1002/2014gl061432
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发表时间：
2014-10-28
影响因子：
5.2
通讯作者：
Dunin-Borkowski, Rafal E.
中科院分区：
文献类型：
--
作者：
Almeida, Trevor P.;Kasama, Takeshi;Dunin-Borkowski, Rafal E.
利用离轴电子全息术研究了在伪单畴（PSD）尺寸范围内（近似0.1-10 μ m）的剩磁感应磁铁矿（Fe 3 O 4）颗粒的热磁行为，PSD尺寸范围在许多岩石岩性的磁性特征中占主导地位。磁感应强度图的建设允许可视化的涡旋域状态在一个单独的Fe 3 O 4颗粒（类似于200纳米的直径）作为温度的函数。在原位加热至700 ℃期间以100 ℃的间隔获得一系列电子全息图证明了Fe 3 O 4颗粒的涡旋状态，在这种情况下，在接近其解阻塞温度时保持热稳定，并且在冷却时表现出类似的面内回复状态;即，该粒子在接近T-C的温度下有效地表现得像单轴单畴粒子。这种粒子被认为是强大的磁记录器。因此，PSD行为的证据不应排除古地磁调查。
The thermomagnetic behavior of remanence-induced magnetite (Fe3O4) particles in the pseudo-single-domain (PSD) size range (similar to 0.1-10 mu m), which dominate the magnetic signature of many rock lithologies, is investigated using off-axis electron holography. Construction of magnetic induction maps allowed for the visualization of the vortex domain state in an individual Fe3O4 grain (similar to 200nm in diameter) as a function of temperature. Acquisition of a series of electron holograms at 100 degrees C intervals during in situ heating up to 700 degrees C demonstrates the vortex state of the Fe3O4 grain, in this instance, remains thermally stable close to its unblocking temperature and exhibits a similar in-plane remanent state upon cooling; i.e., the particle is effectively behaving like a uniaxial single-domain particle to temperatures near T-C. Such particles are thought to be robust magnetic recorders. It is suggested that evidence for PSD behavior should therefore not preclude paleomagnetic investigation.