Solid‐state synthesis and an investigation of the crystal/magnetic structure and magnetic properties of the Bi_1−xCa_xFe_0.6Mn_0.4O_3+δ [x = 0.1, 0.15; δ = 0.02(2)] multiferroics have been conducted to explore an approach to designing ferroelectric materials with the enhanced magnetization attributed to the ferromagnetic superexchange involving the Mn 3d states. It is shown that the (Ca, Mn)‐doped samples maintain the polar R3c structure characteristic of the pure bismuth ferrite. For both these compounds, an antiferromagnetic (AFM) G‐type ordering of the Fe/Mn magnetic moments along the hexagonal c‐axis is revealed at room temperature. The reorientation of the magnetic moments from the c‐ to a‐axis occurs as temperature decreases. Being consistent with the competing character of the superexchange between Mn³⁺, Mn⁴⁺, and Fe³⁺ ions, the coexistence of AFM long‐range‐ordered and superparamagnetic phases underlying the appearance of a significant magnetization in the low‐temperature range is observed.

中文翻译：

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（Ca，Mn）掺杂的铋铁氧体极性相中的低温磁化强度增加和自旋方向转变

Bi _{1- x} Ca _x Fe _0.6 Mn _0.4 O _{3+ δ的}固态合成以及晶体/磁性结构和磁性的研究[ x  = 0.1，0.15; δ  = 0.02（2）]进行了多铁性研究，以探索一种设计具有增强磁化强度的铁电材料的方法，该方法归因于涉及Mn 3d态的铁磁超交换。结果表明，（Ca，Mn）掺杂的样品保持了纯铋铁氧体的极性R3c结构特征。对于这两种化合物，沿六角形的Fe / Mn磁矩的反铁磁（AFM）G型排序c轴在室温下显示。随着温度降低，从c轴到a轴的磁矩会重新定向。与Mn ³⁺，Mn ⁴⁺和Fe ³⁺离子之间的超交换的竞争特征相一致，在低温范围内出现显着磁化的AFM长序相和超顺磁相共存为：观测到的。