The quasi-two-dimensional magnetic topological insulator ${\mathrm{MnBi}}_2{\mathrm{Se}}_4$, stabilized via nonequilibrium molecular beam epitaxy, is investigated by resonant soft x-ray scattering. Kiessig fringes are observed, confirming a high sample quality and a thin film thickness of 10 septuple layers $(\sim 13 \mathrm{nm})$. An antiferromagnetic Bragg peak is observed at the structurally forbidden reflection, whose magnetic nature is validated by studying its temperature, energy, and polarization dependence. Through a detailed analysis, an A-type antiferromagetic order with in-plane moments is implied. This alternative spin structure in ${\mathrm{MnBi}}_2{\mathrm{Se}}_4$, in contrast to the Ising antiferromagnetic states in other magnetic topological insulators, might be relevant for hosting new topological states.

中文翻译：

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通过共振软 X 射线散射探测层状磁拓扑绝缘体 MnBi2Se4 中的反铁磁序

准二维磁拓扑绝缘体${\mathrm{锰铋}}_2{硒}_4$，通过非平衡分子束外延稳定，通过共振软 X 射线散射进行研究。观察到基西格条纹，证实了高样品质量和 10 七层的薄膜厚度$（～13 \mathrm{纳米}）$。在结构禁反射处观察到反铁磁布拉格峰，通过研究其温度、能量和偏振依赖性来验证其磁性性质。通过详细分析，暗示了具有面内矩的A型反铁磁序。这种替代自旋结构${\mathrm{锰铋}}_2{硒}_4$与其他磁拓扑绝缘体中的伊辛反铁磁态相比，可能与容纳新的拓扑态相关。