Combinations of nontrivial band topology and long-range magnetic order hold promise for realizations of novel spintronic phenomena, such as the quantum anomalous Hall effect and the topological magnetoelectric effect. Following theoretical advances, material candidates are emerging. Yet, so far a compound that combines a band-inverted electronic structure with an intrinsic net magnetization remains unrealized. ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ has been established as the first antiferromagnetic topological insulator and constitutes the progenitor of a modular $({\mathrm{Bi}}_2{\mathrm{Te}}_3{)}_n({\mathrm{MnBi}}_2{\mathrm{Te}}_4)$ series. Here, for $n=1$, we confirm a nonstoichiometric composition proximate to ${\mathrm{MnBi}}_4{\mathrm{Te}}_7$. We establish an antiferromagnetic state below 13 K followed by a state with a net magnetization and ferromagnetic-like hysteresis below 5 K. Angle-resolved photoemission experiments and density-functional calculations reveal a topologically nontrivial surface state on the ${\mathrm{MnBi}}_4{\mathrm{Te}}_7(0001)$ surface, analogous to the nonmagnetic parent compound ${\mathrm{Bi}}_2{\mathrm{Te}}_3$. Our results establish ${\mathrm{MnBi}}_4{\mathrm{Te}}_7$ as the first band-inverted compound with intrinsic net magnetization providing a versatile platform for the realization of magnetic topological states of matter.

中文翻译：

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具有周期性Mn亚晶格的MnBi4Te7：ABi2Te3衍生物的拓扑电子结构和本征磁化

非平凡的带拓扑和远距离磁阶的组合有望实现新的自旋电子现象，例如量子反常霍尔效应和拓扑磁电效应。随着理论上的发展，重要的候选人正在涌现。然而，到目前为止，仍未实现将带反转电子结构与固有净磁化强度相结合的化合物。${\mathrm{锰铋}}_{\mathrm{2个}}{特}_4$ 已被确立为第一个反铁磁拓扑绝缘体，并构成了模块化的前身 $（{双}_{\mathrm{2个}}{特}_3{）}_{ñ}（{\mathrm{锰铋}}_{\mathrm{2个}}{特}_4）$系列。在这里$ñ=\mathrm{1个}$，我们确认了与 ${\mathrm{锰铋}}_4{特}_7$。我们在13 K以下建立反铁磁态，然后在5 K以下建立净磁化和类似铁磁的磁滞。${\mathrm{锰铋}}_4{特}_7（0001）$ 表面，类似于非磁性母体化合物 ${双}_{\mathrm{2个}}{特}_3$。我们的结果证明${\mathrm{锰铋}}_4{特}_7$ 作为首个具有固有净磁化强度的带反转化合物，它提供了实现物质磁性拓扑状态的多功能平台。