Un-particle superconductivity in low-dimensional materials

低维材料中的非粒子超导性

基本信息

批准号：
EP/V02986X/1
负责人：
Nigel Hussey
金额：
$ 85.43万
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：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FV02986X%2F1
关键词：
Un particle superconductivity low dimensional

项目摘要

The phenomenon of superconductivity was discovered over a century ago. Over the course of the 20th century, researchers began to unearth its myriad of remarkable properties, including loss-less, high power electrical transmission, magnetic levitation and Josephson tunneling (used to determine fundamental constants with exquisite accuracy). In the 21st century, superconductivity is widely recognised as a pivotal player in the frontier development of quantum computation. On the theoretical side, the definitive theory of superconductivity was published by Nobel laureates John Bardeen, Leon Cooper and Bob Schrieffer over half a century ago. BCS theory proved to be remarkably successful, not only in explaining the properties of many known superconductors, but also in serving as a guide in the search for new superconductors, even those with an unconventional or anisotropic pairing symmetry. Over time, however, a number of superconducting materials have emerged that appear to challenge the BCS template. Significantly, their superconducting properties appear, in many respects, to be superior. Fundamental to BCS theory is the notion that Cooper pairing is an instability of a 'good' metal composed of coherent electronic states with long mean free path. Over the past few decades, however, superconductivity has also been discovered in 'bad' or 'strange metals', i.e. metals that do not conform to the standard models of metallic behaviour. Bad metals are characterized by an electron mean free path (at high temperatures) that diminishes to a fraction of the interatomic distance, while strange metals exhibit an electrical resistivity that grows linearly with temperature effectively from absolute zero right up to their melting point and a response in a magnetic field that follows an entirely different power law dependence to that seen in conventional metals.The core question now is whether BCS theory can account for the emergence of superconductivity in bad or strange metals or whether an entirely new paradigm is required. The fact that the electronic states in bad and/or strange metals lie at the coherent/incoherent boundary suggests that the condensation energy for superconductivity in these materials may derive from a saving in kinetic energy, rather than a saving in potential energy as is the case for BCS superconductors and that the superfluid condensate may emerge from the incoherent, rather than the coherent part of the electron self-energy. We call this alternative paradigm 'un-particle superconductivity'. The goal of this proposal is to explore the viability of un-particle superconductivity in candidate materials via a joint experimental/theoretical research programme that seeks to develop a theoretical framework for pairing of electronic states formed from the incoherent part of the electron spectral function and to test the resulting predictions with precise measurements of their superfluid density and carrier densities (both coherent and incoherent) in the normal, i.e. non-superconducting state. In total, three distinct material classes have been identified as candidate materials for the realization of un-particle superconductivity: copper-oxide high temperature superconductors, iron chalcogenides and one-dimensional purple bronze. Notably, superconductivity in the cuprates was discovered over 35 years ago, yet despite having been subject to the whole spectrum of experimental and theoretical techniques in condensed matter, smoking-gun evidence for BCS-type superconductivity remains elusive. Moreover, cuprates and iron chalcogenides are the only known materials to superconduct in monolayer form and at ambient pressures at temperatures above the boiling point of liquid nitrogen, making them highly attractive as platforms for future quantum computing devices. Finally, fulfillment of our research goals would lead to a new paradigm for (high temperature) superconductivity, one far-removed from the original BCS template.

超导性现象是一个世纪前发现的。在20世纪的过程中，研究人员开始发掘其无数的非凡特性，包括无损耗，高功率电动传输，磁性悬浮和约瑟夫森隧道（用于以精确的精度确定基本常数）。在21世纪，超导性被广泛认为是量子计算边界发展中的关键参与者。从理论方面来说，半个世纪前，诺贝尔奖获得者约翰·巴尔丁（John Bardeen），莱昂·库珀（Leon Cooper）和鲍勃·施里弗（Bob Schrieffer）发表了最终的超导性理论。 BCS理论被证明是非常成功的，不仅在解释了许多已知的超导体的特性，而且还可以作为寻找新的超导体的指南，甚至是具有非常规或各向异性配对对称性的那些超导体。但是，随着时间的流逝，出现了许多超导材料，似乎挑战了BCS模板。值得注意的是，它们的超导性能在许多方面都表现出优势。 BCS理论的基础是，库珀配对是由具有较长平均自由路径的连贯电子状态组成的“良好”金属的不稳定性。然而，在过去的几十年中，在“不良”或“奇怪的金属”中也发现了超导性，即不符合金属行为标准模型的金属。不良金属的特征是电子均值自由路径（在高温下）减少到原子间距离的一小部分，而奇怪的金属表现出一种电阻率，其电阻率与温度有效地从绝对零的熔点到其熔点到其磁性的响应，并且在磁性方面的依赖性依赖于常规的核心问题。不良金属或奇怪金属的超导性，或者是否需要一个全新的范式。 The fact that the electronic states in bad and/or strange metals lie at the coherent/incoherent boundary suggests that the condensation energy for superconductivity in these materials may derive from a saving in kinetic energy, rather than a saving in potential energy as is the case for BCS superconductors and that the superfluid condensate may emerge from the incoherent, rather than the coherent part of the electron self-energy.我们称此替代范式为“ Unparticle超导性”。该提案的目的是通过联合实验/理论研究计划探索候选材料中未颗粒超导的可行性，该计划旨在开发一个理论框架，以配对由电子光谱功能的不相互部分形成的电子状态配对的电子状态，并与所得的预测相关的高度和crose norter and crode and croter and crote and crote and crote and crote and crote and crote norter and crote and crote norter and crote restory（corlured）密度的密度群体构成的构成（即非责任状态。总的来说，已经将三种不同的材料类别确定为实现非颗粒超导性的候选材料：铜 - 氧化物高温超导体，铁粉红色葡萄干剂和一维紫色青铜。值得注意的是，在35年前发现了丘比特的超导性，尽管在冷凝物质中遭受了整个实验和理论技术的影响，但BCS型超导性的吸烟证据仍然难以捉摸。此外，在单层形式和在液氮沸点上方的温度下，铜酸盐和铁葡萄糖生成剂是唯一已知的超导导材料，使其作为未来量子计算设备的平台非常有吸引力。最后，实现我们的研究目标将导致（高温）超导性的新范式，这是与原始BCS模板相比的极远。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Enhanced Superconducting Pairing Strength near a Pure Nematic Quantum Critical Point

DOI：
10.1103/physrevx.13.011032
发表时间：
2022-02
期刊：
Physical Review X
影响因子：
12.5
作者：
K. Mukasa;K. Ishida;S. Imajo;M. Qiu;M. Saito;K. Matsuura;Y. Sugimura;S. Liu;Y. Uezono;T. Otsuka;M. Čulo;S. Kasahara;Y. Matsuda;N. Hussey;T. Watanabe;K. Kindo;T. Shibauchi
通讯作者：
K. Mukasa;K. Ishida;S. Imajo;M. Qiu;M. Saito;K. Matsuura;Y. Sugimura;S. Liu;Y. Uezono;T. Otsuka;M. Čulo;S. Kasahara;Y. Matsuda;N. Hussey;T. Watanabe;K. Kindo;T. Shibauchi

High-temperature superconductivity and strange metallicity: Simple observations with (possibly) profound implications