MnSb2Te4-GeSb2Te4体系中的相平衡及Mn1-xGexSb2Te4固溶体的磁性
Phase equilibria in MnSb2Te4-GeSb2Te4 system and magnetic properties of Mn1-xGexSb2Te4 solid solutions
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中文总结 AI 辅助
研究MnSb2Te4中Ge替代Mn位点的影响，通过高温固相反应合成Mn1-xGexSb2Te4固溶体并表征。发现Ge替代增强顺磁性，有亚铁磁有序，确定两个磁转变及相关特性，为磁输运和拓扑表面态研究提供基础。
中文摘要 AI 辅助
作为反铁磁拓扑绝缘体MnBi2Te4的姊妹化合物，MnSb2Te4也是奇异磁拓扑相的候选材料。另一方面，结构类似但非磁性的相变材料GeSb2Te4也具有非平凡的能带拓扑。受其共同晶体结构、Mn2+和Ge2+相似离子半径以及探索磁性与拓扑相互作用机会的驱动，研究了Ge替代MnSb2Te4中Mn位点的影响。通过高温固相反应合成了Mn1-xGexSb2Te4固溶体，并用SEM-EDS、PXRD、DTA和SQUID对其成分、结构、相行为和磁性进行了表征。Ge替代在整个成分范围内成功，得到均匀的单相样品，通过MnSb2Te4-GeSb2Te4相图证实其通过包晶反应熔化。Ge替代增强了样品的顺磁性，但在x = 0.75之前具有亚铁磁有序，有效磁矩和饱和磁化强度均随Ge含量增加而降低。识别出两个不同的磁转变——高温顺磁到亚铁磁和低温亚铁磁到铁磁，低温磁转变对Ge替代呈穹顶状依赖。在原始MnSb2Te4和x = 0.12替代样品中观察到负磁化，而在x = 0.32和x = 0.55 Ge替代样品中由于竞争磁序出现两个不同的自旋翻转转变。这些发现有助于未来选择性地单晶生长均匀的磁性相，为磁输运和拓扑表面态研究铺平道路。
英文摘要
As a sister compound of the antiferromagnetic topological insulator MnBi2Te4, MnSb2Te4 is also a candidate for exotic magnetic topological phases. On the other hand, the structurally analogous but nonmagnetic phase-change material GeSb2Te4 is also known to exhibit nontrivial band topology. Motivated by their shared crystal structure, the similar ionic radii of Mn2+ and Ge2+, and the opportunity to explore the interplay between magnetism and topology, here we investigate the effects of Ge substitution at Mn sites in MnSb2Te4. The Mn1-xGexSb2Te4 solid solutions were synthesized via high-temperature solid-state reaction and characterized for composition, structure, phase behavior, and magnetism using SEM-EDS, PXRD, DTA, and SQUID. Ge substitution was successful across the full composition range, producing homogeneous, single-phase samples that melt via peritectic reactions, as confirmed by the MnSb2Te4GeS-b2Te4 phase diagram. Ge substitution strengthens the sample's paramagnetism, but with ferrimagnetic ordering up to x = 0.75, with both effective moment and saturation magnetization decreasing with increasing Ge content. Two distinct magnetic transitions - high-temperature paramagnetic to ferrimagnetic and low-temperature ferrimagnetic to ferromagnetic - were identified, with a dome-like shape dependence of the low-temperature magnetic transition on Ge substitution. A negative magnetization was observed in the pristine MnSb2Te4 and x = 0.12 substituted samples, while two distinct spin-flop transitions appeared in the samples with x = 0.32 and x = 0.55 Ge substitutions as a result of competing magnetic orderings. These findings facilitate future selective single-crystal growth of homogeneous, magnetic phases, paving the way for magneto-transport and topological surface states investigations.
