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Electronic structure of the bismuth family of high-temperature superconductors.

机译：高温超导体铋族的电子结构。

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摘要

High temperature superconductivity remains the central intellectual problem in condensed matter physics fifteen years after its discovery. Angle resolved photoemission spectroscopy (ARPES) directly probes the electronic structure, and has played an important role in the field of high temperature superconductors. With the recent advances in sample growth and the photoemission technique, we are able to study the electronic structure in great detail, and address regimes that were previously inaccessible. This thesis work contains systematic photoemission studies of the electronic structure of the Bi-family of high temperature superconductors, which include the single-layer system (Bi2201), the bi-layer system (Bi2212), and the tri-layer system (Bi2223).; We show that, unlike conventional BCS superconductors, phase coherence information emerges in the single particle excitation spectrum of high temperature superconductors as the superconducting peak in Bi2212. The universality and various properties of this superconducting peak are studied in various systems. We argue that the origin of the superconducting peak may provide the key to understanding the mechanism of High-Tc superconductors. In addition, we identified a new experimental energy scale in the bilayer material, the anisotropic intra-bilayer coupling energy. For a long time, it was predicted that this energy scale would cause bilayer band splitting. We observe this phenomenon, for the first time, in heavily overdoped Bi2212. This new observation requires the revision of the previous picture of the electronic excitation in the Brillouin zone boundary. As the first ARPES study of a trilayer system, various detailed electronic properties of Bi2223 are examined. We show that, comparing with Bi2212, both superconducting gap and relative superconducting peak intensity become larger in Bi2223, however, the strength of the interlayer coupling within each unit cell is possibly weaker. These results suggest that the large superconducting phase transition temperature in a high temperature superconductor is associated with parameters that cause both large pairing strength and strong phase coherence in the system. The number of CuO2 layers in each unit cell is just one of the factors that affect these parameters.
机译：高温超导电性发现后的十五年，仍然是凝聚态物理中的核心智力问题。角分辨光发射光谱法（ARPES）直接探测电子结构，并在高温超导体领域中发挥了重要作用。随着样本增长和光电发射技术的最新进展，我们能够更详细地研究电子结构，并解决以前无法访问的机制。本文工作包括对高温超导体双族电子结构的系统光发射研究，包括单层系统（Bi2201），双层系统（Bi2212）和三层系统（Bi2223）。 。;我们证明，与传统的BCS超导体不同，相干信息在高温超导体的单粒子激发光谱中作为Bi2212中的超导峰出现。在各种系统中研究了该超导峰的通用性和各种性质。我们认为，超导峰的起源可能为理解High-Tc超导体的机理提供了关键。此外，我们在双层材料中确定了新的实验能级，即各向异性双层内耦合能。长期以来，据预测该能级会引起双层带分裂。我们首次在重掺杂Bi2212中观察到了这种现象。这种新的观察需要对布里渊区边界中的电子激发的先前图像进行修改。作为对三层系统的第一个ARPES研究，Bi2223的各种详细电子性能得到了检验。我们显示，与Bi2212相比，Bi2223中的超导间隙和相对超导峰强度都变大，但是，每个晶胞内的层间耦合强度可能较弱。这些结果表明，高温超导体中的大超导相变温度与导致系统中大配对强度和强相干性的参数相关。每个晶胞中CuO 2 的层数只是影响这些参数的因素之一。

著录项

  • 作者

    Feng, Donglai.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 128 p.
  • 总页数 128
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 O49;
  • 关键词

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