氧化物Sr4Ru3O10中单层铁磁性的探索

Recently, two-dimensional materials have received much attention due to their potential applications in fabrication of the next generation nano-electronic devices. However, in practical application, there are still many key issues to be solved urgently in order to realize the synergistic operation of various functional devices in a two-dimensional level, and to process and store information efficiently by utilizing both the charge and spin degrees of freedom at the same time, one of them is to look for two-dimensional ferromagnetic materials.. The metallic layered perovskite oxide Sr4Ru3O10 has the characteristics of high chemical stability, strong magnetic anisotropy, and its Curie temperature Tc is not affected by the thickness of at least six unit cells, which is considered as one of the most likely monolayer ferromagnetic materials.. In this proposal, we will further investigate the magnetic properties of Sr4Ru3O10 under the thickness of six unit cells, especially one unit cell, and find out whether there is monolayer ferromagnetism in this material. Meanwhile, we also hope to systematically explore and understand the physical properties of this material when its thickness below few unit cells through the study of this project, so that we can get a better understanding of the multi-interaction about the charge, spin, orbital and lattice degrees of freedom in this material, and to provide a reference for the study of unique behaviors of the (Sr, Ca)n+1RunO3n+1 system.

近年来，二维材料的迅猛发展使人们看到了步入二维电子器件时代的曙光。但在实际应用中，要真正在二维层面上实现各种功能器件的协同运作，以及同时利用电荷与自旋自由度来高效处理、存储信息，仍有许多关键问题亟待解决，其中之一就是寻找铁磁性的二维材料。Sr4Ru3O10具有金属性、高化学稳定性、强磁各向异性以及其居里温度在至少6个原胞厚度下仍不受厚度影响等特性，是当前认为最有可能存在单层铁磁性的材料之一。本课题中，我们将深入开展6个原胞以下尤其是单原胞厚度Sr4Ru3O10的磁性研究，探明Sr4Ru3O10在单原胞时是否仍存在铁磁性的问题，以期从实验的角度推进对二维铁磁性的探索。同时，我们也希望通过本项目的研究，系统的探索并理解该材料在几个原胞尺度下的物性，以期对该材料中的多自由度相互作用有更深入的认识，并为整个(Sr,Ca)n+1RunO3n+1体系的奇异物性研究提供参考。

二维材料的迅猛发展使人们看到了步入“二维电子器件”时代的曙光，但在实际应用中，要实现二维层面上各种功能器件的协同运作，探寻高化学稳定性、高居里温度的单层铁磁材料至关重要。项目以层状钙钛矿氧化物Sr4Ru3O10单晶为研究对象，以探明Sr4Ru3O10材料在超薄尺度甚至单原胞厚度时是否存在铁磁性为核心，通过电、磁输运测量，系统的建立起Sr4Ru3O10的物性，包括电、磁特性随原胞厚度变化的依赖关系。项目实施基本按原计划进行，在研究内容上有适当调整，获得的主要研究成果如下： .1）优化改进并发展了针对4d钌基钙钛矿氧化物的机械解理制备方法，获得了直至2个原胞厚度的超薄样品，并研究了超薄Sr4Ru3O10样品的输运特性。实验发现，在超薄尺度下，Sr4Ru3O10的第二个磁转变被完全抑制，但铁磁转变温度TC却极其稳定，这为找寻新型的TC稳定的超薄铁磁材料提供了新的思路； .2）成功合成了Ru位掺杂Fe原子的Sr4Ru3O10单晶，并研究了其磁行为，实验发现仅仅1%的Fe掺杂，就会使其磁特性发生完全反转，进而解释了元素掺杂引起磁特性反转的物理机制；.3）研究了纳米尺度Fe掺杂Sr4Ru3O10单晶薄片在不同温度和外加磁场下的电输运特性，提出Fe掺杂Sr4Ru3O10可以作为制备自旋电子学功能器件的候选材料。