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Transport and infrared properties of ion irradiated yttrium barium copper oxide thin films.

机译：离子辐照钇钡氧化铜薄膜的传输和红外特性。

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摘要

The discovery of high temperature superconductors prompted the reconsideration of numerous aspects of superconductivity. Among the most fundamental and controversial is the origin of dissipation in a current carrying superconductor. This is also very important from an applied perspective since the onset of dissipation, often described by the critical current density J{dollar}rmsb{lcub}C{rcub},{dollar} determines the current carrying capacity of a material.; In this thesis, low energy, light ion irradiation has been implemented as a means of controlled sample modification. This type of irradiation has the advantage that it does not alter the stoichiometry of the sample but only results in disorder through the creation of point defects. This thesis explores the influence of ion damage on the normal and superconducting properties of {dollar}rm YBasb2Cusb3Osb{lcub}7-delta{rcub}{dollar} thin films. Of particular interest is the contrast between the strong sensitivity of J{dollar}rmsb{lcub}C{rcub}{dollar} and the more modest sensitivity of the critical temperature, T{dollar}rmsb{lcub}C{rcub},{dollar} to ion damage.; The evolution of the temperature dependent resistivity was measured systematically as a function of ion damage. The decrease in T{dollar}rmsb{lcub}C{rcub}{dollar} with ion damage was compared to the predictions of several relevant models. A simple model based on Matthiessen's rule was used to describe the scattering rate and carrier density at low damage levels. At higher damage levels the system undergoes a superconductor-insulator transition which was found to be consistent with the Ioffe-Regel criterion. However, the resistivity in the insulating state is not described by any conventional models for strongly disordered materials.; Measurements of the non-linear electric field-current density characteristics were performed for several levels of ion damage over a range of temperatures and compared with several models for dissipation. The data were found to be well described at all temperatures and damage levels by a model involving the quantum nucleation of vortex loops. The variation of the superconducting carrier density, n{dollar}rmsb{lcub}S{rcub},{dollar} with ion damage was extracted and compared with independent measurements of the same quantity by infrared transmission in identically irradiated {dollar}rm YBasb2Cusb3Osb{lcub}7-delta{rcub}{dollar} thin films. This represents the first time a direct connection has been established between J{dollar}rmsb{lcub}C{rcub}{dollar} and n{dollar}rmsb{lcub}S{rcub}{dollar} in high temperature superconductors.
机译：高温超导体的发现促使人们重新考虑超导的许多方面。最基本和最有争议的问题是载流超导体的耗散起源。从应用的角度来看，这也非常重要，因为耗散的开始（通常用临界电流密度J {dollar} rmsb {lcub} C {rcub}来描述）决定了材料的载流能力。在这篇论文中，低能量的光离子辐照已被实现为可控的样品修饰手段。这种类型的辐照的优点是它不会改变样品的化学计量，而只会通过产生点缺陷而导致混乱。本文探讨了离子损伤对{rm} rm YBasb2Cusb3Osb {lcub} 7-delta {rcub} {dollar}薄膜的正常和超导性能的影响。特别令人感兴趣的是J {dollar} rmsb {lcub} C {rcub} {dollar}的强灵敏度与临界温度T {dollar} rmsb {lcub} C {rcub}的温和灵敏度之间的对比，{美元}损害离子。系统测量了随温度变化的电阻率随离子损伤的变化。将T {dollar} rmsb {lcub} C {rcub} {dollar}随离子损伤的减少与几种相关模型的预测进行了比较。使用基于Matthiessen规则的简单模型来描述低损伤水平下的散射速率和载流子密度。在较高的损伤水平下，系统会经历超导体-绝缘体的转变，这与艾菲尔-雷格尔标准相符。但是，对于任何无序的材料，任何常规模型都没有描述绝缘状态下的电阻率。在一定温度范围内对几种离子损伤水平进行了非线性电场-电流密度特性的测量，并与几种耗散模型进行了比较。发现该数据通过涉及涡旋环量子成核的模型在所有温度和损伤水平下均能很好地描述。提取具有离子损伤的超导载流子密度nrmsb {lcub} S {rcub}和美元的变化，并将其与在相同辐射的{rm} rm YBasb2Cusb3Osb { lcub} 7-delta {rcub} {dollar}薄膜。这代表在高温超导体中的J {dollar} rmsb {lcub} C {rcub} {dollar}和n {dollar} rmsb {lcub} S {rcub} {dollar}之间首次建立直接连接。

著录项

  • 作者

    Moffat, Steven H.;

  • 作者单位

    McMaster University (Canada).;

  • 授予单位 McMaster University (Canada).;
  • 学科 Physics Condensed Matter.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 145 p.
  • 总页数 145
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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