Quasiparticle Spectroscopic Studies of the Pairing State and Competing Orders in Hole- and Electron-Doped Cuprate Superconductors

空穴和电子掺杂铜酸盐超导体的配对状态和竞争顺序的准粒子光谱研究

• 批准号: 0405088
• 负责人: Nai-Chang Yeh
• 金额: $ 37.5万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0405088&HistoricalAwards=false
• 关键词: Quasiparticle; Spectroscopic; Studies; Pairing; State

High-temperature superconducting cuprates are doped Mott insulators with strong electronic correlation. Depending on the doping level (d) and the sign of the dopant (hole- or electron-doping) in the CuO(2) planes, the electronic and structural anisotropies, and disorder, different competing orders can emerge in the ground state of these cuprates. These competing orders give rise to various non-universal phenomena that have masked better understanding for the pairing mechanism of cuprate superconductivity. The primary objective of this project is to unravel the physical origin of various non-universal phenomena and to identify truly ubiquitous characteristics among all cuprates. The technical approach will involve systematic experimental studies of hole- and electron-doped cuprates of different doping levels (d) and with controlled substitutions of quantum impurities, using a new homemade variable-temperature high-field-compatible scanning tunneling microscope (STM) and other auxiliary characterization tools in the PI's group. In addition, numerical computations of the quasiparticle local density of states (LDOS) for different model Hamiltonians will be performed. The proposed research is of significant educational value because of the range of experimental skills and the depth of theoretical knowledge required of the participants to accomplish the tasks. Successful completion of the research can scientifically advance current understanding of the pairing mechanism of cuprate superconductivity and of the competing orders in other strongly correlated electronic systems, whereas technologically the STM instrumentation expertise can benefit research on novel nano-scale materials and devices.The physical cause for the occurrence of high-temperature superconductivity (HTS) in the cuprate superconductors remains a mystery despite substantial research progress since the discovery of HTS in 1986. The primary reason for the lack of complete theoretical understanding is due to the variety of low-temperature physical phases that can exist in different families of cuprate superconductors upon simple "tuning" of the chemical properties of these materials. This research project intends to unveil the mystery of HTS by investigating how different physical phases occur in the cuprates, and to identify the truly ubiquitous characteristics among all cuprates that are responsible for HTS. The experimental approach involves systematic studies of different cuprates using a homemade variable-temperature high-field-compatible scanning tunneling microscope (STM) and other auxiliary characterization tools in the PI's group at Caltech. The STM measurements can provide important information about the cuprates with atomic-scale spatial resolution. In addition to the experiments, computer modeling will be performed for comparison with experimental data. The proposed research is of significant educational value because of the range of experimental skills and the depth of theoretical knowledge required of the participants to accomplish the tasks. Successful completion of this project can advance the theoretical understanding and commercial applications of cuprate superconductors. The STM instrumentation developed for this project can further benefit the characterization of novel nano-scale structures and devices in the emerging field of nano-science & technology.

高温超导铜氧化物是一种掺杂的Mott绝缘体，具有很强的电子关联。根据掺杂水平（d）和CuO（2）平面中掺杂剂的符号（空穴或电子掺杂）、电子和结构各向异性以及无序，这些铜酸盐的基态中可以出现不同的竞争顺序。这些竞争秩序引起了各种非普遍的现象，掩盖了更好地理解铜氧化物超导的配对机制。该项目的主要目标是解开各种非普遍现象的物理起源，并确定所有铜酸盐中真正普遍存在的特征。技术方法将涉及系统的实验研究空穴和电子掺杂的铜酸盐的不同掺杂水平（d）和量子杂质的控制取代，使用一个新的自制的可变温度高场兼容扫描隧道显微镜（STM）和其他辅助表征工具在PI的组。此外，数值计算的准粒子局域态密度（LDOS）的不同模型的哈密顿量将被执行。由于参与者完成任务所需的实验技能和理论知识的深度，拟议的研究具有重要的教育价值。这项研究的成功完成可以科学地推进目前对铜氧化物超导性配对机制以及其他强关联电子系统中竞争有序的理解，而在技术上，STM仪器的专业知识可以有利于新的纳米尺度材料和器件的研究。自1986年发现高温超导体以来，尽管研究取得了很大进展，但铜氧化物超导体的物理性质仍然是一个谜。缺乏完整理论理解的主要原因是由于在简单“调整”这些材料的化学性质后，不同铜酸盐超导体家族中可能存在各种低温物理相。该研究项目旨在通过研究铜酸盐中如何发生不同的物理相来揭开高温超导的神秘面纱，并确定所有铜酸盐中真正普遍存在的特性。实验方法包括使用自制的变温高场兼容扫描隧道显微镜（STM）和加州理工学院PI小组的其他辅助表征工具对不同的铜酸盐进行系统研究。STM测量可以提供具有原子尺度空间分辨率的铜氧化物的重要信息。除了实验之外，还将进行计算机建模以与实验数据进行比较。由于参与者完成任务所需的实验技能和理论知识的深度，拟议的研究具有重要的教育价值。该项目的成功完成将促进对铜酸盐超导体的理论理解和商业应用。为该项目开发的STM仪器可以进一步有利于表征新兴纳米科学技术领域中的新型纳米尺度结构和器件。