金属有机框架材料的磁性与多铁性研究

Magnetoelectric(ME) multiferroic materials have been attracted much attention due to their great potential in many applications on improving the speed of the electronic device, energy efficiency and miniaturization of the circuit .Most work is currently focusing on inorganic materials.To further search the new single phase multiferroic materials is becoming one of the most important topics. Metal-Organic Frameworks (MOFs) combine merits from both organic functional groups with advantages of lead free, chirality, easy synthesis and tailorality, and inorganic metal (or metal-salts) with magnetism. The coexistence of (anti)ferroeletricity and (anti)ferromagnetism can be realized in MOFs.In this project, the magnetism and multiferroicity of MOFs including the structures of ABX3 etc. will be well studied systematically. The multiferroicity will be introduced by the design of organic functional groups, organic ligands and metal(or metal-salts) in MOFs.The correlation among the organic ligands, spin configurations and multiferroicity will be investigated by the experimental measurements of magnetism, transport, permittivity, pyroelectric current, static and dynamic magnetoelectric effects etc. In addition, the electron spin resonance (ESR) and neutron scattering will be used to study the crystal structure and microscopic magnetic structure.The ME effects will be investigated systematically induced by external fields on the basis of the coexistence of the designed magnetic structures and the polar ligands.The microscopic mechanism of ME effects will be revealed based on the above experiments.

磁电多铁性材料在提高电子器件的速度，能量使用效率以及电路小型化方面存在广阔的应用前景。目前大部分的研究工作都集中在无机多铁材料上，进一步探索新的单相磁电多铁材料成为多铁领域的重点研究方向之一。金属有机框架材料可以结合有机配体官能团的优点如无铅、手性、易制备及易裁减,和无机金属（或金属盐）的磁性，实现铁电有序和磁有序的共存。本项目将系统研究金属有机框架材料中的磁性和多铁性，研究体系包括AMX3等结构的金属有机框架材料。通过对有机官能团，桥联配体和金属(或金属盐)的结构设计引入磁电多铁性。利用磁性、铁电、介电、热释电、静态和动态的磁电耦合效应等宏观物性的测量，结合磁共振，中子散射等先进实验方法，研究有机配位体和金属离子（或金属盐）对磁结构及多铁性关联的物理规律，并通过外加物理场对磁结构和极性配位体的调控来系统研究磁电效应，并阐明其产生的微观机理。

磁电多铁性材料在提高电子器件的速度，能量使用效率以及电路小型化方面存在广阔的应用前景。目前大部分的研究工作都集中在无机多铁材料上，进一步探索新的单相磁电多铁材料成为多铁领域的重点研究方向之一。金属有机框架(MOFs)可以结合有机配体官能团的优点，如无毒性，手性，易制备，易裁减和无机金属的磁性，实现铁电有序和磁有序的共存。本项目系统研究了钙钛矿结构的金属有机框架材料(MOFs) [DMA]M(HCOO)3 (M=Mn,Fe,Cu)以及[CH3NH3)]2CuCl4的结构、磁性、电极化与磁电耦合效应。主要研究结果和进展体现在以下四个方面：1)利用缓慢蒸发法生长了系列[DMA]M(HCOO)3 (M=Mn,Fe,Cu)以及[CH3NH3)]2CuCl4单晶材料。2)通过磁性，电输运，介电，静态磁电耦合等宏观物性的测量，结合磁共振等先进实验方法，研究了MOFs中磁性与多铁性。3) 通过外加物理场对磁组态或氢键的调控实现了有效的正逆磁电耦合效应。4)在[(CH3)2NH2]Fe(HCOO)3中观察到了磁化强度与磁电耦合效应的共振量子隧穿效应。研究成果已在国际知名学术期刊Phys.Rev.Lett., JACS, Appl.Phys.Lett.等发表SCI论文10篇。