Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders.
Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders.
复制标题
直接观察非理想磁铁矿记录仪中磁性涡流结构的热消电。
DOI：
10.1002/2016gl070074
复制
发表时间：
2016-08-28
影响因子：
5.2
通讯作者：
Dunin-Borkowski, Rafal E.
中科院分区：
文献类型：
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作者：
Almeida, Trevor P.;Muxworthy, Adrian R.;Kovacs, Andras;Williams, Wyn;Nagy, Leslei;Conbhui, Padraig O.;Frandsen, Cathrine;Supakulopas, Radchagrit;Dunin-Borkowski, Rafal E.
利用离轴电子全息术研究了控制许多火成岩中磁信号的伪单畴（PSD）磁铁矿（Fe3O4）颗粒的热退磁。通过构建和检查磁感应图，实现了在原位加热过程中单个Fe3O4颗粒（直径约250 nm）所保持的涡旋结构的可视化。在加热到居里温度以上时，以与体热退磁测量类似的方式进行的剩磁诱导的Fe3O4颗粒的逐步退磁显示，其涡旋状态在接近其解阻塞温度的加热下保持稳定，并且在冷却时以相同或相反的涡旋恢复。因此，PSD Fe3O4颗粒表现出与单畴载体相当的热磁行为，因此，涡旋态被认为是古地磁研究的可靠磁性记录器。非理想磁铁矿颗粒的热退磁涡旋态磁化强度随温度变化的可视化涡旋结构是可靠的古地磁信号记录器
The thermal demagnetization of pseudo‐single‐domain (PSD) magnetite (Fe3O4) particles, which govern the magnetic signal in many igneous rocks, is examined using off‐axis electron holography. Visualization of a vortex structure held by an individual Fe3O4 particle (~250 nm in diameter) during in situ heating is achieved through the construction and examination of magnetic‐induction maps. Stepwise demagnetization of the remanence‐induced Fe3O4 particle upon heating to above the Curie temperature, performed in a similar fashion to bulk thermal demagnetization measurements, revealed that its vortex state remains stable under heating close to its unblocking temperature and is recovered upon cooling with the same or reversed vorticity. Hence, the PSD Fe3O4 particle exhibits thermomagnetic behavior comparable to a single‐domain carrier, and thus, vortex states are considered reliable magnetic recorders for paleomagnetic investigations. Thermal demagnetization of nonideal magnetite particles Visualized magnetization of vortex state with temperature Vortex structures are reliable paleomagnetic signal recorders