Investigation of the strange metal normal state of electron-doped oxide superconductors

电子掺杂氧化物超导体奇异金属正常态的研究

基本信息

批准号：
2002658
负责人：
richard greene
金额：
$ 48万
依托单位：
University of Maryland, College Park
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2002658&HistoricalAwards=false
关键词：
Investigation strange metal normal state

项目摘要

Non-technical abstractSuperconductivity, the complete absence of electrical resistance, is an amazing low temperature property of some elements and compounds. This property of solids was discovered in 1911 and was believed to be fully understood in 1957 by the Bardeen, Cooper, Schrieffer (BCS) theory. In 1987 some copper oxide compounds (cuprates) were discovered with unexpectedly high superconducting transition temperatures (up to 140 Kelvin). This high-temperature superconductivity cannot be explained by the conventional BCS mechanism and it is not presently understood. A complete understanding of high-temperature superconductivity is one of the major unsolved problems of condensed matter physics. The solution to this problem could lead to the discovery of room temperature (300 Kelvin) superconductors, a development with very significant practical applications. This project performs experimental studies on one class of cuprate compounds where the superconductivity can be completely eliminated by the application of a small magnetic field. This enables the non-superconducting, or normal, metallic state to be studied over a wide range of temperature from 600 K to well below 1K. The normal state of the cuprates has quite different physical properties from those of well-known metals, such as copper or lead, and the cuprates have been called strange metals. An understanding of this strange metal state is believed to be crucial for an understanding of the origin of the superconductivity. In this project a variety of transport and other experiments are performed on specially prepared thin films. Variation of the magnetic field, the temperature and electron doping can change the normal state properties in ways that are expected to give deep insight into the nature of the strange metal state and the superconductivity. This project supports the education of PhD and undergraduate students at the University of Maryland---an urban university with a diverse population---in advanced vacuum deposition and electrical characterization techniques. These techniques have proven to be excellent training for productive scientific careers in academic and technology settings.Technical abstractUnderstanding the mechanism of superconductivity and the non-Fermi liquid (strange metal) normal state in strongly correlated oxides is one of the most significant unsolved problems of condensed matter physics. Recently some dramatic experimental results have been reported by the PI (and others) that give new insights into the physics of the copper oxides (cuprates) and that also report the discovery of superconductivity in a related nickelate system, Sr doped NdNiO2. This project follows up on these breakthroughs to gain a more detailed understanding of the strange normal state of the electron-doped cuprates and the doped nickelates. This project provides a comprehensive set of experiments to study the nature of the normal state when superconductivity is suppressed, either by magnetic field, disorder or critical current. The electron-doped cuprates are particularly advantageous for this research because the low temperature normal state (0 T Tc) can be reached with a modest dc magnetic field (H 10 T). An understanding of the nature of the normal state of the cuprates is believed to be crucial for understanding the cause of high-temperature superconductivity in the cuprates. The experimental techniques used are resistivity, Hall Effect, magnetoresistance, Nernst effect, thermopower, specific heat and strain (pressure). Some transport experiments are done at very high magnetic field at the NSF supported National High Magnetic Field Laboratory (NHMFL) in Tallahassee and Los Alamos. The research includes an in-depth study of the itinerant ferromagnetism discovered by the PI in 2019 in the highly doped region of the n-type cuprates The combination of materials science expertise and physics measurement expertise of the PI is essential for making progress in this very important area of correlated physics materials research. This project incorporates the training of high-school students, undergraduate science majors, graduate students, and postdoctoral scientists in various experimental aspects of condensed matter physics research. As in the past, the principal investigator will encourage women and underrepresented groups to participate in this project. The external collaborations in this project provide a unique vehicle for students to experience research in different laboratory environments, i.e., university, industry, and government. An ongoing participation in the Graduate Resources Advancing Diversity (GRADMAP) program at the University of Maryland will involve undergraduates in research exposure programs designed to attract a broader audience to graduate studies. Efforts to encourage a broader education in science via existing Physics department outreach programs with predominately minority public-school students near the University of Maryland will be continued. These include, Physics is Phun, Physics Discovery Days, and the Summer School Girl’s Program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术抽象的特殊性（完全没有电阻）是某些元素和化合物的惊人低温特性。固体的这种特性在1911年被发现，并被认为在1957年被Bardeen，Cooper，Schrieffer（BCS）理论完全理解。 1987年，发现了一些氧化铜化合物（铜），并具有出乎意料的高超导过渡温度（高达140 kelvin）。传统的BCS机制无法解释高温超导性，也不能理解。对高温超导性的完全理解是凝结物理学的主要未解决问题之一。解决此问题的解决方案可能导致发现室温（300 Kelvin）超导体，这是具有非常重要的实际应用的开发。该项目对一类库酸酯化合物进行了实验研究，在该化合物中，可以通过应用小磁场完全消除超导性。这使得在600 K到远低于1K以下的温度范围内可以研究非抑制或正常的金属状态。丘比特的正常状态与铜或铅等知名金属的物理特性截然不同，而铜层被称为奇怪的金属。人们认为对这种奇怪的金属状态的理解对于理解超导性的起源至关重要。在这个项目中，对特殊准备的薄膜进行了各种运输和其他实验。磁场，温度和电子掺杂的变化可以以期望对奇怪金属状态和超导性的性质的方式改变正常状态。该项目支持马里兰州大学的博士学位和本科生的教育 - 一所城市大学，具有多样性的人口 - 高级真空沉积和电气表征技术。事实证明，这些技术是在学术和技术环境中对产品科学职业的出色培训。技术抽象理解超导性的机制和在密切相关的氧化物中的非Fermi液体（奇怪的金属）正常状态是凝聚态物理学的最重要的未解决的问题之一。最近，PI（和其他）报道了一些引人注目的实验结果，这些结果给出了对铜氧化物（铜酸盐）物理学的新见解，并且还报告了相关镍系统中超导性的发现，SR掺杂NDNIO2。该项目遵循这些突破，以对电子掺杂的酸辣椒和掺杂的镍的奇怪正常状态有了更详细的了解。该项目提供了一组全面的实验，以研究磁场，混乱或关键电流抑制超导性时，研究正常状态的性质。掺杂电子的铜岩对于这项研究特别有利，因为可以使用适度的直流磁场（H 10 T）达到低温正常状态（0 T TC）。据信，对丘比特正常状态的性质的理解对于理解铜酸盐中高温超导性的原因至关重要。所使用的实验技术是耐药性，霍尔效应，磁性，Nernst效应，热电器，特定的热量和应变（压力）。一些运输实验是在NSF支持的国家高磁场实验室（NHMFL）和Los Alamos的NSF支持的国家高磁场实验室（NHMFL）进行的。这项研究包括对PI在N型铜层的高度掺杂区域中发现的巡回铁磁学的深入研究，PI的材料科学专业知识和物理测量专业知识的组合对于在这项非常重要的相关物理学材料研究的非常重要的领域中取得了进步。该项目纳入了高中生，本科科学专业，研究生和博士后科学家的培训，这些培训是在凝聚态物理学研究的各个实验方面的培训。与过去一样，首席研究人员将鼓励妇女和代表性不足的团体参加该项目。该项目的外部合作为学生提供了独特的工具，可以在不同的实验室环境（即大学，工业和政府）中进行研究。持续参与马里兰州大学多样性的研究生资源（GradMap）计划将涉及本科生参加研究曝光计划，旨在吸引更广泛的受众群体学习研究生研究。通过现有物理学系的外展计划鼓励科学教育的努力将继续与马里兰州大学附近的主要少数公立学校学生进行。其中包括物理学是Phun，Physics Discovery Days和The Summer School's计划。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准，被视为通过评估而被视为珍贵的支持。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Counterexample to the conjectured Planckian bound on transport

推测的普朗克运输约束的反例

DOI：
10.1103/physrevb.104.235138
发表时间：
2021
期刊：
Physical Review B
影响因子：
3.7
作者：
Poniatowski, Nicholas R.;Sarkar, Tarapada;Lobo, Ricardo P.;Das Sarma, Sankar;Greene, Richard L.
通讯作者：
Greene, Richard L.

BCS d -wave behavior in the terahertz electrodynamic response of electron-doped cuprate superconductors

电子掺杂铜酸盐超导体太赫兹电动响应中的 BCS d 波行为

DOI：
10.1103/physrevb.104.064501
发表时间：
2021
期刊：
Physical Review B
影响因子：
3.7
作者：
Tagay, Zhenisbek;Mahmood, Fahad;Legros, Anaelle;Sarkar, Tarapada;Greene, Richard L.;Armitage, N. P.
通讯作者：
Armitage, N. P.

Hidden strange metallic state in underdoped electron-doped cuprates

欠掺杂电子掺杂铜酸盐中隐藏的奇怪金属态

DOI：
10.1103/physrevb.103.224501
发表时间：
2021
期刊：
Physical Review B
影响因子：
3.7
作者：
Sarkar, Tarapada;Poniatowski, Nicholas R.;Higgins, Joshua S.;Mandal, P. R.;Chan, Mun K.;Greene, Richard L.
通讯作者：
Greene, Richard L.

Anomalous normal-state magnetotransport in an electron-doped cuprate

电子掺杂铜氧化物中的反常常态磁输运