Transport in Unconventional Superconductors

9600105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赫希菲尔德理论研究，并开发低于临界温度的实用输运理论。主要的焦点将是无序和磁场对低温性质的影响。以前的理论已经很好地描述了实验结果，通过脏的d波图反映了无序依赖的准粒子态密度。将执行d波序参数的散射幅度的计算，包括自洽的非对角线散射，以试图解决这种最简单的模型在描述输运性质方面的不足。对该理论的这种修正可能不会被忽视，而且很可能会引入质的新物理学。在所有阶段，都将与各向异性S波态进行比较，以寻找质的差异。理论中的几个例子，其中偏离通常的模型球面或椭球费米面可能会导致定性的新的影响，将被调查。例子包括UPt3的E2u配对情形中传输系数的伪各向同性被六边形各向异性破坏，以及由于YBCO和BSCCO的d波模型中的正交性而创建用于非对角散射的矩阵元素。最后，我们将计算非常规超导体在有限磁场中的输运性质，考虑到非常规涡旋晶格最显著的不寻常特征，例如在整个涡旋上大量的非束缚准粒子激发。这将涉及到对电子从单个d波涡的散射截面的仔细分析。然后建立了包含杂质散射的半微观输运理论，并将其应用于超导态的热导、电导和霍尔系数的测量。将对高温超导体和所谓的重费米子超导体中超导电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。***

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. ***