Preparation and experimental studies on unconventional superconductors

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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