Strongly correlated electron physics in novel materials

物质的基本物理理论已经知道了几十年，但越来越多的科学家正在发现挑战其中一些公认原理的材料，在这些新的化合物类别中，有相当大的技术创新潜力。然而，在我们可以跑步之前，我们必须步行，并且需要对这些新特性的物理原理有充分的了解，这样材料才能按照我们的意愿弯曲。值得注意的是，最近的研究指出了我们的金属标准理论中的明显错误，其根本原因是组成电子之间的强烈相互作用。传统上，电子-电子相互作用在金属中被认为是可以忽略的，通常被忽视。然而，在过去的几十年里，已经发现了一些新的材料，其中电子相互作用能与电子的动能(或平动能)相当；电子被称为“强关联”。这些系统不仅似乎违反了金属的标准理论，而且经常表现出惊人的磁性现象。一个特别令人振奋的方面是，这些现象为我们提供了极好的技术发展机会。事实上，在过去几十年中发现的几个新的关联电子系统已经被用于固态设备。例如，用于移动电话网络的变电站采用了高T_c铜酸盐超导体，以及利用了Fe/Cr/Fe三层膜的巨磁电阻特性的新的磁读取头技术。这项科学研究计划的中心是生产和研究奇异材料，目标是发现新的关联电子量子态。它集中了两个未被探索的材料家族，我们相信应该为相关电子领域的研究提供新的和有趣的途径。这项研究在性质上是基础的，但受益于与电子设备开发非常明确的联系，因为新的电子量子现象为应用科学提供了极好的机会。从更广泛的角度来看，材料物理代表着科学创新的新前沿。物理学家类似于勇敢的探险家，他们渴望发现和冒险，开始探索和绘制世界地图。在他们的冒险过程中，这些先驱们发现了一些关于我们星球的令人震惊的事实，这些事实挑战了许多长期持有的概念性观点，例如，世界并不像之前假设的那样是平的，而是球形的。以类似的方式(尽管危险要小得多！)，我们希望发现令人兴奋的新现象，挑战我们目前对自然的看法，并加强我们对我们生活的宇宙的理解。正是这种发现的兴奋驱使材料物理学的人们探索和量化奇怪的新化合物，希望有一天能让所有人都受益。

The basic physical theories of matter have been known for many decades but increasingly scientists are uncovering materials that challenge some of these accepted tenets, and within these new classes of compounds there is considerable potential for technological innovation. However, before we can run we must walk and a full understanding of the physics of these novel properties is required so the materials can be bent to our will. Notably, recent research has pointed to glaring errors in our standard theory of metals, the underlying cause of which are strong interactions between the constituent electrons. Traditionally, electron-electron interactions have been treated as negligible within metals and generally ignored. However, over the last few decades novel materials have been uncovered in which electron interaction energies are comparable to the electronic kinetic (or translational) energies; the electrons are said to be 'strongly correlated'. As well as appearing to defy the standard theories of metals these systems quite often display striking magnetic phenomena. A particularly exciting aspect is that these phenomena offer us excellent opportunities for technological development. Indeed, several new correlated electron systems discovered in the last few decades have been adapted for solid state devices. Examples include substations for mobile phone networks that incorporate the high-Tc cuprate superconductors and new magnetic read head technologies that exploit the giant magnetoresistance properties of the Fe/Cr/Fe trilayers. This scientific research proposal is centred on producing and studying exotic materials with the goal of discovering new correlated electron quantum states. It focuses two unexplored families of materials, the niobates and iridates that we believe should provide new and interesting avenues of research in the correlated electron field. The research is fundamental in nature but benefits from a very clear connection to electronic device development since new electronic quantum phenomena offer excellent opportunities for applied science.On a broader view, the physics of materials represents a new frontier for scientific pioneering. Physicists are analogous to the intrepid explorers who, in their thirst for discovery and adventure, set out to explore and map the world. In their course of their adventures, those pioneers discovered some startling facts about our planet that challenged many long-held conceptual viewpoints, for example the world was not flat, as had been previously supposed, but spherical. In a similar manner (although with considerably less danger!), we hope to uncover exciting new phenomena that challenge our current perceptions of nature and enhance our understanding of the universe that we live in. It is this thrill of discovery that drives people in materials physics to explore and quantify strange new compounds that will hopefully one day benefit all.