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将进行旨在帮助确定氧化铜和重费米子超导体的配对状态的理论研究，并发展临界温度以下的实用传输理论。 主要的焦点将是无序和磁场对低温性能的影响。 以前的理论提供了一个很好的描述，反映了无序依赖的准粒子态密度的实验结果在一个肮脏的d波图片。 将进行d波序参量的散射振幅的计算，包括自洽的非对角散射，试图解决这种最简单的模型在描述输运性质中的不足之处。 这种对理论的修正可能不会被忽视，并且很可能引入新的物理学。 在所有阶段，将与各向异性s波状态进行比较，以寻找质的差异。 在理论中的几个实例，偏离通常的模型球形或椭球形费米表面可以导致定性的新效果将被调查。 例子包括六方各向异性的E2U配对的情况下UPt3的输运系数的伪各向同性的打破，和创建的矩阵元素的非对角散射由于正交性的d波模型YBCO和BSCCO。 最后，非常规超导体在有限磁场中的输运性质将被计算，占最显着的非常规涡旋晶格的不寻常的功能，如在整个涡旋的大密度的非束缚准粒子激发。 这将涉及到对电子从单个d波涡旋散射截面的仔细分析。 一个半微观输运理论，包括杂质散射，然后将制定和应用于测量的热和电的铝电导率和霍尔系数的超导状态。 将对高温超导体和所谓的重费米子超导体的超导性的各个方面进行理论研究。 特别是，将研究输运性质以及无序和磁场对超导态性质的影响。 ***