铁基反钙钛矿结构金属功能材料的性能调控与微观物理机制探索

The Youth Natural Science Foundation puts particular emphasis on the studies of the crystal structure, magnetic, electrical transport and their chemical doping effects for a series of iron-based antiperovskite AXFe3. It has been found that there are many potential functionalities such as room-temperature magnetocaloric, giant-magnetoresistance, low temperature coefficient of resistivity and thermoelectricity. Based on the observed experimental results, several electron-doped phase diagrams are plotted and the relevant phenomena could be explained reasonably combined with the first-principles calculations. However, the present work just focuses on exploring the novelty of this system or functional properties, to explore its optimized regulation of the functionality, and deep microscopic mechanism isn’t mentioned yet. In order to expand the applications of iron-based anti-perovskite materials in magnetic refrigeration, microelectronic devices prospects, this project attempts to further optimize the functionality of this system (such as magnetocaloric efffect and low temperature coefficient of resistivity) from three different angles (double-doped or rare-earth alternative、reducing the dimension of the film as well as extreme experimental conditions); By scaling the relations between the relevant physical properties and control parameters, to clarify the characteristics of several typical functional features of the system. By establishing appropriate theoretical model, to explain its underlying physical mechanism, strive to understand the functional properties of the system from both experimental and theoretical point of view, which may provide an important reference for the material design.

青年基金项目系统研究了系列铁基反钙钛矿结构AXFe3的晶体结构、磁性、电输运等基本物性以及元素掺杂对物性的影响，初步窥探到该体系具有室温磁热、巨磁阻、低电阻率温度系数及热电等潜在功能属性。基于实验规律绘出了多个电子掺杂相图，并结合第一性原理的计算对相关实验现象提出了合理的解释。然而已开展的工作侧重探索该体系中的新奇物性或功能属性，对其功能属性的优化调控和深层微观物理机制的探索尚未涉及。为了拓展铁基反钙钛矿材料在磁致冷、微电子器件等方面的应用前景，本项目尝试从三个不同的角度(双掺杂或稀土替代、降低维度的薄膜化以及极端实验条件)对其中的典型功能属性(如磁热和低电阻率温度系数)进行进一步的优化调控;通过考察相关物性随调控参量变化的标度行为，弄清该体系中几个典型功能属性的特征；建立恰当的理论模型，解释其深层的物理机制，力求从实验和理论两个角度系统地了解该体系的功能属性，为材料设计提供重要参考。

本项目系统研究了反钙钛矿结构铁基碳化合物ACFe3及氮化物ANFe3 (A = Ga, Al, Sn, Zn, Cu)的晶体结构、磁、电输运等无物性以及电子掺杂/压力调控对该体系化合物物性的影响。揭示了该体系不仅具有潜在的功能属性(如：室温磁热效应、巨磁电阻、室温附近零电阻率温度系数以及热电等)而且存在奇特的磁以及电输运行为(如：GaCFe3-xCox和Sn1-xNFe3+x中自旋阻挫冻结，GeNFe3中的反常霍尔现象，Sn1-xNFe3+x中的Griffiths相等)。通过掺杂进一步优化了该体系中具有潜在应用前景的功能属性材料：室温磁热效应(GaCFe3-xMnx、ZnCFe3-xCox等)、巨磁电阻效应(GaCMn3-xFex等)、室温下宽温区零电阻率温度系数(GaCFe3-xCox等)以及热电材料(SnCCo3系列化合物)。我们总结了电子掺杂的递变规律，绘制出电子掺杂相图(GaCFe3-xMnx、ZnCFe3-xCox、GaCFe3-xCox、Sn1-xNFe3+x、Sn1-xGexNFe3等)，结合计算模拟解释了相关实验现象。本项目取得的研究成果对反钙钛矿结构化合物体系研究具有重要的推动作用，发现了一些十分有趣的物理现象，为今后对该领域的深入研究提供重要信息；也为该系列化合物的应用功能(如磁制冷、微电子器件等)的探索和应用提供了重要的参考依据。