钙钛矿型过渡金属氧化物中基于电荷有序的磁电物性研究

Multiferroicity of perovskite transition metal oxides has become a hot topic of condensed matter physics due to the abundant physical properties and broad potential applications, in which the coexistence and coupling between magnetism and ferroelectricity have attracted much attention, especially for the materials with excellent multiferroic performance. Recently, multiferroic materials with charge-ordering-induced ferroelectricity present enormous potentials in exploring the promising properties, then, to better understand the underlying physical mechanisms and explore more multiferroics (charge-ordering driven) in transition metal oxides with perovskite structure, here we propose to study the electronic structures, charge-ordered state and corresponding magnetic and electronic properties of target materials by using the first-principles calculation. In particular, we will start from the material composition and lattice structure to find out more materials with charge-ordered state in single-phase materials and heterostructures. For these systems, multiply factors such as strain, pressure, doping and interfacial states, will be systematically studied to reveal their physical influence on charge-ordered state. The goal is to make the materials with charge-ordered state demonstrate multiferroicity and magnetoelectricity through symmetry analysis and the well-controlled manners. Our project will enrich the magnetoelectric physics originated from charge-ordering and push forward the development of memory devices.

钙钛矿过渡金属氧化物中的多铁性因其丰富的物理内涵和广阔的应用前景成为当前凝聚态物理的研究热点。其中关于如何实现磁性与铁电性共存耦合以及寻找出优异磁电耦合性能材料的两个方向研究倍受关注。目前由电荷有序诱导的铁电性多铁材料在探索优异磁电耦合效应方面展现出了巨大的潜力，为了更好地理解其物理内涵并在钙钛矿过渡金属氧化物中挖掘出更多的电荷有序型多铁材料，本项目拟通过第一性原理计算来研究目标材料的电子结构、电荷有序态及其诱导的磁电物性。具体而言，本项目将从材料组成以及晶格构型出发，在单相材料以及薄膜异质结中寻找出更多具有电荷有序态的材料；关注应变、压强、掺杂、界面态等因素对电荷有序态的影响。目标是通过材料本身的对称性以及相应的调控手段使得具有电荷有序态的材料呈现出多铁性以及磁电耦合效应。本项目的研究将丰富基于电荷有序的磁电物理内涵，对推动存储器件的发展具有重要的研究意义。

项目执行期间，我们开展了钙钛矿过渡金属氧化物和相关体系物理性质的理论研究，并做了一些理论与实验相结合的探索。. 首先，我们综述了钙钛矿过渡金属氧化物的磁性、铁电性以及磁电耦合效应。其次，我们研究了钙钛矿过渡金属氧化物异质结界面处的奇特性质，比如电荷转移诱导的磁性，金属绝缘转变的调控，自旋极化的二维电子气，铁电调控的自旋极化二维电子气等。最后，为拓展研究，我们对其它相关结构过渡金属化合物的电子结构、磁矩以及量子态的调控也进行了细致的研究，发现了诸多有意义的物理特性。. 本项目的研究成果对深入理解钙钛矿过渡金属氧化物及其衍生体系的物理性质，推动相关器件设计具有一定的研究价值和意义。