Here, we report successful single crystal growth of new possible magnetic topological insulator (MTI) FeBi₂Te₄ by a self-flux method via a vacuum encapsulation process. The detailed Rietveld analysis of powder XRD data shows the as-grown MTI crystal to be mainly dominated by the FeBi₂Te₄ phase along with minority phases of Bi₂Te₃ and FeTe. Scanning electron microscope (SEM) image shows the morphology of as-grown MTI single crystal to be of layered type laminar structure. Raman spectroscopy of the crystal exhibited three distinct phonon modes at 65, 110, and 132 cm⁻¹ along with two split secondary modes at 90, and 144 cm⁻¹. The secondary split modes are the result of FeTe intercalation in the Bi₂Te₃ unit cell. Magnetoresistance (MR%) measurement has been performed at different temperatures, i.e., 200 K, 20 K, and 2 K in applied magnetic fields up to ± 12 Tesla, which showed very low MR in comparison with pure Bi₂Te₃ crystal. Temperature dependence of DC magnetization measurements shows the FeBi₂Te₄ crystal to be mainly of ferromagnetic (FM) or ferrimagnetic nature above 295 K, albeit a secondary weak magnetic transition is seen at 54–46 K as well. Detailed isothermal magnetization (MH) results showed that the FM saturation moment at 295 K is 0.00213 emu/g, which is nearly invariant until 400 K. In summary, we had grown an MTI FeBi₂Te₄ single crystal, which may be a possible entrant for the quantum anomalous Hall (QAH) effect at room temperature or above.

中文翻译：

---

新型磁性拓扑绝缘子FeBi 2 Te 4的晶体生长和表征

在这里，我们报告了通过真空封装工艺通过自磁通方法成功地实现了新型可能的磁性拓扑绝缘体（MTI）FeBi ₂ Te ₄的单晶生长。粉末XRD数据的详细Rietveld分析显示，生长的MTI晶体主要由FeBi ₂ Te ₄相以及Bi ₂ Te ₃和FeTe的少数相组成。扫描电子显微镜（SEM）图像显示，成膜的MTI单晶为层状层状结构。晶体的拉曼光谱在65、110和132 cm ^-1处表现出三种不同的声子模式，在90和144 cm ^-1处表现出两种分裂的次级模式。。次分裂模式是Bi ₂ Te ₃晶胞中FeTe嵌入的结果。磁阻（MR％）测量是在不同温度下进行的，即在高达±12 Tesla的外加磁场中，分别在200 K，20 K和2 K下进行测量，与纯Bi ₂ Te ₃晶体相比，MR值非常低。直流磁化强度的温度依赖性显示FeBi ₂ Te ₄晶体在295 K以上时主要具有铁磁性（FM）或亚铁磁性，尽管在54–46 K处也观察到次级弱磁转变。详细的等温磁化（MH）结果表明，在295 K处的FM饱和矩为0.00213 emu / g，直到400 K为止几乎不变。总而言之，我们已经生长了MTI FeBi ₂ Te ₄单晶，这可能是可能的。室温或更高温度下量子异常霍尔（QAH）效应的进入者。