分馏作为控制CaMn_{2+x}Al_{10-x}中Mn/Al位点混合与磁性的工具
Fractionation as a Tool to Control Mn/Al Site Mixing and Magnetism in CaMn_{2+x}Al_{10-x}
- Ames National Laboratory, U.S. Department of Energy, Iowa State University（艾姆斯国家实验室，美国能源部，爱荷华州立大学）
- Department of Physics and Astronomy, Iowa State University（爱荷华州立大学物理与天文系）
- Faculty of Applied Physics and Mathematics and Advanced Materials Center, Gdansk University of Technology（格但斯克理工大学应用物理与数学学院及先进材料中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过分馏法生长CaMn_{2+x}Al_{10-x}晶体，发现过量Mn含量随倾析温度降低而减少，并证明先前归因于化学计量比化合物的磁性实为过量Mn不均匀分布所致，分馏有助于区分本征磁性与无序效应。
AI中文摘要：
我们报道了采用分馏方法生长的CaMn_{2+x}Al_{10-x}晶体的单晶生长及物理性质表征。从相同的初始熔体组成中获得了三个连续批次，系统地采样了Ca-Mn-Al三元相图中相邻的狭窄区域。单晶X射线衍射测量揭示了Mn/Al位点混合，过量Mn浓度x随倾析温度的降低而系统性减小。磁化强度的低温上升和电阻率的最大值均随过量Mn含量的减少而逐渐减弱，这表明先前归因于化学计量比CaMn_{2}Al_{10}的磁性实际上源于过量Mn原子的不均匀分布。更广泛地说，本工作结果表明，分馏有助于区分本征磁性与与磁性离子不均匀分布相关的无序诱导效应，特别是在考虑巡游磁性时，对于具有有限形成宽度的材料而言。
英文摘要：
We report single crystal growth and physical property characterization of CaMn_{2+x}Al_{10-x} crystals grown using a fractionation approach. Three consecutive batches were obtained from the same initial melt composition, systematically sampling neighboring, narrow regions of the ternary Ca-Mn-Al phase diagram. Single-crystal X-ray diffraction measurements reveal Mn/Al site mixing, with the excess Mn concentration, x, decreasing systematically with decreasing decanting temperature. A low-temperature upturn in magnetization and a maximum in electrical resistivity both become progressively weaker with decreasing excess Mn content, suggesting that the previously reported magnetic properties attributed to stoichiometric CaMn_{2}Al_{10} instead arise from an inhomogeneous distribution of excess Mn atoms. More broadly, the results presented in this work demonstrate how fractionation can help distinguish intrinsic magnetic behavior from disorder-induced effects associated with an inhomogeneous distribution of magnetic ions in materials with a finite width of formation, particularly when itinerant magnetism is under consideration.
