Structure Property Relationships in Transition Metal Oxides

该项目涉及一类表现出挫败感的材料。其含义与《牛津英语词典》的定义不太一样，其中动词“frustrate”被定义为“犹豫”或“失望”，派生的名词、形容词和副词都表达了相同的“失望”意思。在我们的定义中，涉及的是竞争性交互、约束或命令。想象一个具有许多通过电线或线程连接的站点或节点的网络。 如果这些站点中的大量站点受到相互冲突的需求的影响，那么整个系统就会受到挫败。例如，假设每个站点都存在一个指向特定方向的箭头。有关每个站点的箭头方向的信息由连接线传送。如果通过电线来自两个相邻站点的命令存在竞争，即，如果一个命令使箭头指向上方，另一个命令使箭头指向下方，那么我们在该站点就会感到沮丧。挫败感的概念渗透到现代科学的许多领域，在蛋白质折叠、位错传播甚至天体物理学等不同主题中都能找到。基于等边三角形网络或晶格的磁性材料提供了最清晰的挫败感表达。受挫的磁铁经常表现出奇怪的特性。例如，它们似乎经常违反热力学第三定律，该定律规定，当温度接近绝对零时，所有空间无序都必须消失。就箭头而言，它们必须全部排成一行以形成有序的图案。挫败感充其量只能使这一过程变得困难，而真实的材料通常会发现普通材料中观察不到的意想不到的空间图案。我们的目标是识别可能会受挫的磁性材料，将它们冷却到低温并尝试解开所显示的图案。这些发现不仅将阐明磁挫败领域，还将阐明挫败概念出现的几个相关领域。**

This project concerns a class of materials which exhibit frustration. What is meant is not quite the same as the Oxford English Dictionary definition where the verb, frustrate, is defined as to balk or disappoint and the derived nouns, adjectives and adverbs all convey the same idea disappointment. In our definition what is involved are competing interactions, constraints or commands. Imagine a network with many sites or nodes connected by wires or threads. If a significant number of these sites are subject to conflicting demands, then the entire system is said to be frustrated. For example, take the case where at each site there exists an arrow pointing in a specific direction. Information about the direction of the arrow at each site is conveyed by the connecting wires. If the commands from two adjacent sites through the wires are in competition, i.e., if one command is for the arrow to point up and the other for the arrow to point down, then we have frustration at that site. The concept of frustration permeates many areas of modern science, being found in such disparate topics as protein folding, dislocation propagation and even astrophysics. Magnetic materials based on equilateral triangular networks or lattices provide the cleanest expression of frustration. Frustrated magnets often exhibit bizarre properties. For example they often seem to violate the Third Law of Thermodynamics which states that as the temperature approaches absolute zero, all spatial disorder must disappear. In the case of the arrows, they must all line up to form a well ordered pattern. Frustration renders this difficult at best and real materials will often find unexpected spatial patterns which are not observed in ordinary materials. Our goal is to identify magnetic materials which are likely to be frustrated, cool them down to low temperatures and attempt to unravel the patterns displayed. The discoveries made will illuminate not only the field of magnetic frustration but also the several related areas in which the concept of frustration arises.**