发表机构
Hainan University; Arizona State University; Institute of High Energy Physics, Chinese Academy of Sciences; Spallation Neutron Source Science Center; University of Science and Technology Beijing; Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（海南大学; 亚利桑那州立大学; 中国科学院高能物理研究所; 散裂中子源科学中心; 北京科技大学; 中国科学院物理研究所北京凝聚态物理国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究发现尖晶石氧化物Mg0.5Fe0.5TiFeO4的磁结构耦合可在低温下驱动Fe/Mg发生位点再分布，揭示了关联尖晶石氧化物中低温阳离子迁移的新机制。
AI 中文摘要
氧化物中的离子传输通常在低温下被冻结，此时热能远低于典型的阳离子迁移势垒。中子粉末衍射显示，尖晶石Mg0.5Fe0.5TiFeO4在从200 K冷却至5 K的过程中，四面体（A位）与八面体（B位）之间发生Fe/Mg的逐步再分布；在5 K时，A位Fe占有率在Rietveld分辨率范围内增至接近完全占据，而Ti则保留在B位。这种交换与复杂的磁关联有关，而非经典的热激活窗口。低温磁致伸缩体积变化表明存在强自旋-晶格耦合，但无法将磁致伸缩确定为唯一的热力学驱动力。室温高压X射线衍射呈现相反的占有率趋势，表明仅体积收缩无法解释低温位点交换。这些结果表明，磁结构自由能最小化是关联尖晶石氧化物中低温阳离子迁移的合理机制。
英文摘要
Ionic transport in oxides is generally frozen at cryogenic temperatures, where thermal energy lies far below typical cation-migration barriers. Neutron powder diffraction reveals progressive Fe/Mg redistribution between tetrahedral (A) and octahedral (B) sites in the spinel Mg0.5Fe0.5TiFeO4 upon cooling from 200 K to 5 K. A-site Fe occupancy increases toward near completion at 5 K within Rietveld resolution, while Ti remains on the B site. This exchange coincides with complex magnetic correlations rather than a classical thermally activated window. Low-temperature magnetostrictive volume changes indicate strong spin-lattice coupling, but do not identify magnetostriction as the sole thermodynamic driver. Room-temperature high-pressure X-ray diffraction produces the opposite occupancy trend, showing that volume contraction alone cannot explain the cryogenic site exchange. These results point to magneto-structural free-energy minimization as a plausible mechanism for unlocking cryogenic cation mobility in a correlated spinel oxide.
Comments17 pages, 4 figures. Submitted to National Science Review. Updated author list; revised manuscript
