Hematite carries magnetic signals of interest in tectonic, paleoclimatic, paleomagnetic, and planetary studies. First-order reversal curve (FORC) diagrams have become an important tool for assessing the domain state of, and magnetostatic interactions among, magnetic particles in such studies. We present here FORC diagrams for diverse hematite samples, which provide a catalog for comparison with other studies and explain key features observed for hematite. Ridge-type signatures typical of uniaxial single-domain particle assemblages and “kidney-shaped” FORC signatures, and combinations of these responses, occur commonly in natural and synthetic hematite. Asymmetric features that arise from the triaxial basal plane anisotropy of hematite contribute to vertical spreading in kidney-shaped FORC distributions and are intrinsic responses even for magnetostatically noninteracting particles. The dominant FORC distribution type in a sample (ridge, kidney-shaped, or mixture) depends on the balance between uniaxial/triaxial switching. The identified signals explain magnetization switching and anisotropy features that are intrinsic to the magnetic properties of hematite and other materials with multiaxial magnetic anisotropy.

中文翻译：

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赤铁矿 (α-Fe2O3) 中的磁畴状态和各向异性来自一阶反转曲线图

赤铁矿携带在构造、古气候、古地磁和行星研究中感兴趣的磁信号。在此类研究中，一阶反转曲线 (FORC) 图已成为评估磁性粒子的畴状态和静磁相互作用的重要工具。我们在此展示了各种赤铁矿样品的 FORC 图，这些图提供了与其他研究进行比较的目录，并解释了对赤铁矿观察到的关键特征。单轴单域粒子组合的典型脊型特征和“肾形”FORC 特征以及这些响应的组合，通常出现在天然和合成赤铁矿中。由赤铁矿的三轴基面各向异性引起的不对称特征有助于肾形 FORC 分布的垂直扩散，并且即使对于静磁非相互作用粒子也是内在响应。样品中的主要 FORC 分布类型（脊形、肾形或混合物）取决于单轴/三轴切换之间的平衡。识别出的信号解释了赤铁矿和其他具有多轴磁各向异性的材料的磁性所固有的磁化转换和各向异性特征。