Three‐dimensional geometries of silicate‐hosted magnetic inclusions from the Harcus intrusion, South Australia have been determined using focused‐ion‐beam nanotomography (FIB‐nt). By developing an effective workflow, the geometries were reconstructed for magnetic particles in a plagioclase (162) and a pyroxene (282), respectively. For each inclusion, micromagnetic modeling using Micromagnetic Earth Related Rapid Interpreted Language Laboratory provided averaged hysteresis loops and backfield remanence curves of 20 equidistributed field directions together with average M_s, M_rs, H_c, and H_cr. The micromagnetic structures within each silicate are single‐domain (SD), single‐vortex (SV), multivortex (MV) and multidomain states. They have been analyzed using domain‐state diagnostic plots, such as the Day plot and the Néel plot. SD particles can be subdivided into groups with dominant uniaxial anisotropy (M_rs/M_s ∼0.5 and 10 < H_c < 100 mT) and mixed uniaxial/multiaxial anisotropy (M_rs/M_s ∼0.7 and 10 < H_c < 30 mT). Most SV particles lie on a trend with 0 < M_rs/M_s < 0.1 and 0 < H_c < 10 mT, while others display a broad range of intermediate M_rs/M_s and H_c values. SV and MV states do not plot on systematic grain‐size trends. Instead, the multicomponent mixture of domain states within each silicate spans the entire range of natural variability seen in bulk samples. This questions the interpretation of bulk average hysteresis parameters in terms of grain size alone. FIB‐nt combined with large‐scale micromagnetic simulations provides a more complete characterization of silicate‐hosted carriers of stable magnetic remanence. This approach will improve the understanding of single‐crystal paleomagnetism and enable primary paleomagnetic data to be extracted from ancient rocks.

中文翻译：

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天然磁铁矿集合体的磁滞现象：基于聚焦离子束纳米断层扫描的硅酸盐基质磁铁矿包裹体微磁学

使用聚焦离子束纳米断层扫描（FIB-nt）确定了来自南澳大利亚州哈克斯（Harcus）入侵的硅酸盐质磁性包裹体的三维几何形状。通过开发有效的工作流程，分别重构了斜长石（162）和辉石（282）中磁性粒子的几何形状。对于每个包含物，使用与微磁地球相关的快速解释语言实验室进行的微磁建模提供了平均磁滞回线和20个均匀分布场方向的后场剩磁曲线以及平均M _s，M _rs，H _c和H _cr。每种硅酸盐中的微磁结构为单畴（SD），单涡旋（SV），多涡旋（MV）和多畴态。已使用域状态诊断图对它们进行了分析，例如Day图和Néel图。SD粒子可以细分为具有主要单轴各向异性（M _rs / M _s约0.5和10 < H _c <100 mT）和混合单轴/多轴各向异性（M _rs / M _s约0.7和10 < H _c <30 mT）的组）。大多数SV粒子处于0 < M _rs / M _s <0.1和0 < H _c的趋势<10 mT，而其他显示的中间M _rs / M _s和H _c值范围很宽。SV和MV状态并未绘制出系统的晶粒尺寸趋势。取而代之的是，每种硅酸盐中畴态的多组分混合物跨越了散装样品中可见的自然变化的整个范围。这质疑仅凭晶粒尺寸来解释体均磁滞参数。FIB-nt与大规模微磁学模拟相结合，可以更完整地表征具有稳定剩磁的硅酸盐载体。这种方法将增进对单晶古磁学的理解，并使从古岩石中提取原始古磁数据。