Transport in Unconventional Superconductors

非常规超导体中的输运

• 批准号: 9600105
• 负责人: Peter Hirschfeld
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9600105&HistoricalAwards=false
• 关键词: Transport; Unconventional; Superconductors

9600105 Hirschfeld Theoretical research designed to aid in the identification of the pairing state of the copper oxide and heavy fermion superconductors and the development of a practical theory of transport below the critical temperature will be conducted. The primary focus will be on the effect of disorder and magnetic field on low-temperature properties. Previous theory has provided a good description of experimental results reflecting the disorder-dependent quasiparticle density of states in terms of a dirty d-wave picture. Calculations of the scattering amplitude for a d-wave order parameter will be performed, including self-consistent off diagonal scattering, in an attempt to address inadequacies of the simplest models of this kind in the description of transport properties. Such corrections to the theory may not be ignored and are likely to introduce qualitatively new physics. At all stages, comparisons will be made with anisotropic s-wave states to search for qualitative differences. Several instances in the theory where deviations from the usual model spherical or ellipsoidal Fermi surface can lead to qualitatively new effects will be investigated. Examples include the breaking of spurious isotropy of transport coefficients in the E2u pairing scenario for UPt3 by hexagonal anisotropy, and the creation of matrix elements for off-diagonal scattering due to orthorhombicity in the d wave model for YBCO and BSCCO. Finally, transport properties of unconventional superconductors in a finite magnetic field will be calculated, accounting for the most significant unusual features of the unconventional vortex lattice, such as the large density of unbound quasiparticle excitations over the entire vortex. This will involve a careful analysis of the scattering cross-section for electrons from a single d-wave vortex. A semimicroscopic transport theory including impurity scattering will then be formulated and applied to measurements of thermal and electric al conductivities and Hall coefficients in the superconducting state. %%% Theoretical research will be conducted on various aspects of superconductivity in the high temperature superconductors and the so-called heavy-fermion superconductors. In particular, studies will be made of transport properties and on the effects of disorder and magnetic fields on superconducting state properties. ***

9600105 Hirschfeld 将进行理论研究，旨在帮助识别氧化铜和重费米子超导体的配对状态，并开发临界温度以下的实用输运理论。 主要关注点是无序和磁场对低温特性的影响。 先前的理论对实验结果提供了很好的描述，反映了脏 d 波图像中与无序相关的准粒子态密度。 将执行 d 波阶参数的散射幅度的计算，包括自洽的非对角线散射，试图解决此类最简单模型在传输特性描述中的不足之处。 对理论的这种修正可能不会被忽视，并且很可能引入新的物理学性质。 在所有阶段，都将与各向异性横波状态进行比较，以寻找质的差异。 将研究理论中的几个实例，其中偏离常用模型球面或椭球体费米面可能会导致定性的新效应。 示例包括通过六方各向异性破坏 UPt3 的 E2u 配对场景中输运系数的杂散各向同性，以及由于 YBCO 和 BSCCO 的 d 波模型中的正交性而创建非对角散射的矩阵元素。 最后，将计算有限磁场中非常规超导体的输运特性，解释非常规涡旋晶格最显着的异常特征，例如整个涡旋上未束缚准粒子激发的大密度。 这将涉及对来自单个 d 波涡旋的电子的散射截面进行仔细分析。 然后将制定包括杂质散射的半微观输运理论，并将其应用于超导状态下的热导率、电导率以及霍尔系数的测量。 %%% 将在高温超导体和所谓的重费米子超导体中的超导性的各个方面进行理论研究。 特别是，将研究输运特性以及无序和磁场对超导态特性的影响。 ***