The intersection of topology and magnetism represents a new playground to discover novel quantum phenomena and device concepts. In this work, we show that under certain synthetic conditions, a van der Waals single-crystalline compound $\mathrm{MnS}{\mathrm{b}}_{1.8}\mathrm{B}{\mathrm{i}}_{0.2}\mathrm{T}{\mathrm{e}}_4$ exhibits a net ferromagnetic state with a Curie temperature of 26 K, in contrast to the fully compensated antiferromagnetic order observed previously for other members of the $\mathrm{Mn}{\left(\mathrm{Sb},\mathrm{Bi}\right)}_2\mathrm{T}{\mathrm{e}}_4$ family. We employ magneto-transport, bulk magnetization, x-ray and neutron scattering studies to illustrate the structural, magnetic, and electrical properties of $\mathrm{MnS}{\mathrm{b}}_{1.8}\mathrm{B}{\mathrm{i}}_{0.2}\mathrm{T}{\mathrm{e}}_4$. Our structural analyses reveal considerable Mn-Sb site mixing and suggest a recently proposed mechanism, where Mn occupying the Sb site mediates a ferromagnetic coupling between Mn layers [Murakami et al., Phys. Rev. B 100, 195103 (2019)], could be at play. Close comparisons made to an antiferromagnetic compound $\mathrm{MnS}{\mathrm{b}}_2\mathrm{T}{\mathrm{e}}_4$ illustrate the subtle magnetic interactions of the system and the important role played by local chemistry. The appearance of an unusual anomalous Hall effect in $\mathrm{MnS}{\mathrm{b}}_{1.8}\mathrm{B}{\mathrm{i}}_{0.2}\mathrm{T}{\mathrm{e}}_4$ at low temperatures hints at a magnetic ground state different from other members of this family. Our results are an important step in the synthesis and understanding of magnetism in materials with topological characteristics.

中文翻译：

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范德华化合物中的铁磁性MnSb1.8Bi0.2Te4

拓扑和磁性的交集代表了一个发现新的量子现象和器件概念的新场所。在这项工作中，我们证明了在某些合成条件下，范德华斯单晶化合物$锰{\mathrm{b}}_{1.8}\mathrm{乙}{\mathrm{一世}}_{0.2}\mathrm{Ť}{\mathrm{Ë}}_4$ 呈现出居里温度为26 K的净铁磁态，与先前观察到的其他成员的完全补偿的反铁磁阶相反。 $锰{（锑，双）}_2\mathrm{Ť}{\mathrm{Ë}}_4$家庭。我们采用磁输运，体磁化，X射线和中子散射研究来说明金属的结构，磁性和电学性质。$锰{\mathrm{b}}_{1.8}\mathrm{乙}{\mathrm{一世}}_{0.2}\mathrm{Ť}{\mathrm{Ë}}_4$。我们的结构分析揭示了大量的Mn-Sb位置混合，并提出了最近提出的机制，其中Mn占据Sb位置在Mn层之间介导了铁磁耦合[Murakami等。，物理 版本B 100，195103（2019）]，可能是在玩耍。与反铁磁性化合物的紧密比较$锰{\mathrm{b}}_2\mathrm{Ť}{\mathrm{Ë}}_4$说明了系统的微妙磁相互作用以及局部化学作用。出现异常的霍尔效应$锰{\mathrm{b}}_{1.8}\mathrm{乙}{\mathrm{一世}}_{0.2}\mathrm{Ť}{\mathrm{Ë}}_4$低温提示其磁性基态不同于该家族的其他成员。我们的结果是合成和理解具有拓扑特征的材料中的磁性的重要一步。