Preparation and experimental studies on unconventional superconductors

在传统超导体中，超流是由S-波库珀对携带的。在非传统超导体中，对波函数可能是奇宇称自旋三重态，也可能是奇偶宇称的某种混合体。在具有非中心对称结构的材料中，即缺乏反转中心的系统中，宇称不再是一个好的量子数，以及在具有强烈的自旋-轨道耦合的材料中，例如含有4d和5d金属的材料中，可以发现非传统的超导电性。在这个实验项目中，这两组超导体将是学生工作的重点。非常规超导性质将被研究包括奇异的超导带隙结构(超导带隙中的线或节点)，磁电效应，如螺旋相和超过泡利极限的上临界场，时间反转对称性破坏，甚至拓扑效应。学生将准备多晶和单晶样品。用X射线衍射仪和电子显微镜对样品的结构性质进行了研究。然后，学生将学习这些材料在低温和强磁场下的正常和超导态特性。除了我们实验室的实验，我们还将使用国家和国际中央设施提供的一系列中子散射和Muon光谱技术来研究这些材料的物理。这些项目旨在帮助更好地了解是什么驱动了非常规超导，包括那些具有应用潜力的超导体。更具体地说，该项目将集中对几种新的超导材料的性质进行全面调查。目标将是准备这些新材料并完成对其正常和超导性质的研究，包括在国际同行评议的期刊上发表结果。这项研究属于EPSRC研究领域超导和凝聚态：电子结构

In conventional superconductors the supercurrents are carried by s-wave Cooper pairs. In unconventional superconductors, the pair wave function may be an odd-parity spin-triplet, or perhaps some mixture of even and odd parity. Unconventional superconductivity may be found in materials with noncentrosymmetric structures, i.e. systems which lack a centre of inversion where parity is no longer a good quantum number, and in materials with strong spin-orbit coupling, e.g. those containing 4d and 5d metals. In this experimental project it will be these two groups of superconductors that will be the focus of the student's work. The unconventional superconducting properties that will be investigated include exotic superconducting gap structures (lines or nodes in the superconducting gap), magnetoelectric effects such as a helical phase and upper critical fields exceeding the Pauli limit, time reversal symmetry breaking, and even topological effects.The student will prepare polycrystalline and single crystal samples. The structural properties of the samples will be studied using x-ray diffraction and electron microscopy. The student will then study the normal and superconducting state properties of these materials at low temperatures and in high magnetic fields. As well as experiments in our laboratories, a range of neutron scattering and muon spectroscopy techniques available at national and international central facilities will also be used to investigate the physics of these materials.The projects aims to help build a better understanding of what drives unconventional superconductivity, including those superconductors with potential for use in applications. More specifically, the project will focus on the comprehensive investigation of the properties of several new superconducting materials. The objectives will be the preparation of these new materials and the completion of studies of their normal and superconducting properties, including publication of the results in international peer-reviewed journals. The research falls under the EPSRC research areas Superconductivity and Condensed Matter: Electronic Structure