Frustration and reduced dimensionality as routes to new forms of quantum order

挫折和降维作为通向新形式量子秩序的途径

• 批准号: EP/G031460/1
• 负责人: Nigel Hussey
• 金额: $ 74.93万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG031460%2F1
• 关键词: Frustration; reduced; dimensionality; routes; new; Frustration; reduced; dimensionality; routes; new

When steam cools down, fast-moving water molecules condense into water. And if this water is cooled further, the watermolecules stop moving altogether, and organize themselves into the beautiful crystal structures we know as ice. All ofthe materials we use to make electronic devices --- for example the semi-conductor brain'' of the computer you arenow using - contain mobile electrons in a liquid or gas-like state. So what happens to these electrons when they cooldown ? The answer depends on the chemical structure of material in which they live.In some materials the electrons form a solid, rather like the water molecules in ice. Some become magnetic. And somebecome superconductors'' - a remarkable type of metal whose electrical resistivity is exactly zero. Such systemsare said to exhibit different forms of order'', which is to say that the electrons they contain organize themselvesin different ways when they are cooled down. One of the most important themes in 21st century materials science is thesearch for materials whose electrons exhibit completely new forms of order. This is a problem as fundamental as thesearch for new types of elementary particle. But it is also one of profound technological significance, since thesenew materials may one day be used to build new forms of electronic device.This proposal combines state-of-the-art theory and experiment, with the goal of exploring how new forms of quantumorder can arise in systems where no simple form of order wins outright, and the electrons are frustrated (muchlike people) by the bewildering array of choices which they face. The experimental systems we consider are at the forefront of modern materials science, and are unique in their physical behaviour. In LiV2O4, vanadium d-electrons become as massive as muons.In Na4Ir3O8, magnetic Ir ions fail to order magnetically at any temperature. PrBa2Cu4O8 is the most one-dimensional metal known to exist, whilst the organic compounds kappa-(ET)2Cu2(CN)3 and kappa-(ET)2Cu[N(CN)2]Cl, provide a long-sought realization of quantum spins on a highly-frustrated triangular lattice.Our main experimental approach will be to measure how these systems transport heat and electricity. The ratio of thermal and electrical conductivities, measured over a range of temperatures, is a very sensitive test of the way in which the electrons in a given material have organized themselves. Measuring this ratio will enable us to establish that these materials are completely unlike conventional metals and insulators. We will also study how their electronic characteristics, such as mass, evolve as the systems become more frustrated. At the same time, we will use super-computers to solve mathematical models of how unconventional order might work in these and materials. In particular we try to understand how electrons work together to form new types of elementary excitation'', for example particles with half the charge of an electron ! If successful, this work has the potential to change how we think about metals forever...

当蒸汽冷却时，快速移动的水分子将凝结成水中。而且，如果将这种水进一步冷却，则水分子会完全停止移动，并将自己整理成我们所知道的冰的美丽晶体结构。我们用来制造电子设备的所有材料 - 例如，您使用的计算机使用的半导体大脑' - 在液体或气体状状态下包含移动电子。那么，这些电子冷却时会怎样？答案取决于它们所使用的材料的化学结构。在某些材料中，电子形成固体，就像冰中的水分子一样。有些变成磁性。和某些型超导体' - 一种非凡的金属类型，其电阻率完全为零。这种系统据说表现出不同形式的秩序“”，也就是说，在冷却时，它们所包含的电子在各种方式中都不同。 21世纪材料科学中最重要的主题之一是对电子具有全新秩序形式的材料的搜索。这与对新类型的基本粒子的搜索一样的基本问题。但这也是技术意义的深刻意义之一，因为该提案可能有一天可以用来建造新形式的电子设备。该提议结合了最新的理论和实验，目的是探索探索新形式的量子订单形式如何在没有简单形式的秩序形式的系统中出现，而这些简单的秩序形式却赢得了直接赢得电子效果，并且通过沮丧的（很多人），他们会通过像孔沃尔德（Bewilsing）相处ordeces and and and and and and and and and and and and and and and and and and and and and。我们考虑的实验系统位于现代材料科学的最前沿，其身体行为是独一无二的。在liv2o4中，钒d-电子与muons.in na4ir3O8一样大，磁性红外离子在任何温度下都无法磁锁定。 PRBA2CU4O8是已知存在的最一维金属，而有机化合物Kappa-（et）2CU2（CN）3和Kappa-（et）2Cu [n（cn）2] cl，可在高度效率的三角形效果上进行量子旋转的长期实现。在一系列温度下测量的热导电率的比率是对给定材料中的电子本身组织的方式非常敏感的测试。测量该比率将使我们能够确定这些材料与常规金属和绝缘子完全不同。随着系统变得更加沮丧，我们还将研究它们的电子特性（例如质量）如何发展。同时，我们将使用超级计算机来解决这些和材料中非常规秩序如何起作用的数学模型。特别是我们试图了解电子如何共同形成新型的基本激发”，例如，具有一半电荷的粒子！如果成功，这项工作有可能改变我们永远对金属的看法...