毕业论文移动版

摘要正确理解铜氧化物高温超导体赝能隙的起源问题被认为是探索高温超导微观机理的一个外围突破。Yang-Rice-Zhang(YRZ)框架是描述赝能隙现象的一种重要的唯象理论，然而在YRZ框架下无法自洽的确定不同掺杂浓度时的赝能隙[即共振价键（RVB）能隙]和超导能隙，这严重限制了YRZ框架的应用。本文在YRZ框架的基础上提出了一种可以自洽确定RVB和超导能隙的理论，理论计算的RVB、超导能隙以及谱函数随掺杂浓度的变化趋势不仅与YRZ框架中采用经验能隙公式的计算结果一致，也与角分辨率光电子能谱实验中费米面的变化一致。我们的理论将极大地扩展YRZ框架的应用范围，对深入理解赝能隙形成的可能机制、进一步认识高温超导机理提供了帮助。52386

A correct understanding of the origin of the pseudogap in high temperature cuprate superconductors is considered to be a peripheral breakthrough in the understanding of the microscopic mechanism of high temperature superconductivity. Yang-Rice-Zhang (YRZ) framework is an important phenomenological theory to describe the phenomenon of pseudogap. However, in the framework of YRZ, the pseudogap [resonant valence bond (RVB) gap] and the superconducting gap are unable to have a self consistent determination at different doping concentrations, and this severely limits the application of the YRZ framework. Based on the YRZ framework, this paper presents a theory of a self consistent determination of RVB and superconducting gap. The doping dependence of the self consistent calculations of RVB, superconducting gap and spectral function are not only consistent with the calculated results of the empirical gap formula in the YRZ framework, but also consistent with the doping dependence of the Fermi surface observed in the angular resolved photoelectron spectroscopy experiments. Our theory will greatly extend the application of YRZ framework, and will provide help for a deep understanding of the origin of pseudogap as well as a further understanding of the mechanism of high temperature superconductivity.

毕业论文关键词：超导； 赝能隙； 费米弧；RVB能隙； 格林函数

Keyword: superconductivity；pseudogap； Fermi arc；RVB gap；the Green function

目    录

1. 背景介绍 4

2. 赝能隙起源问题 4

图 1 铜氧化物超导体的相图 5

2.1 YRZ模型 6

图 2 掺杂浓度为x=0.1时的费米弧 7

图 3 掺杂浓度为x=0.16时的费米弧 7

图 4 掺杂浓度为x=0.2时的费米面 8

3. 理论和模型 8

图 5 RVB能隙随掺杂浓度的大小变化 9

4. 结果和分析 10

图 6 掺杂浓度为x=0.05时的费米弧 11

图 7 掺杂浓度为x=0.1时的费米弧 11

图 8 掺杂浓度为x=0.15时的费米弧 12

图 9 掺杂浓度为x=0.2时的费米面 12

图 10 K. Fujita等人测得的不同掺杂下费米弧的变化 13

图 11 RVB能隙和超导能隙随掺杂浓度的大小变化 13

参考文献 15

致谢 (责任编辑：qin)