Muon spin rotation/relaxation investigations of magnetism in superconductors and coordination polymers

该提案将主要利用新建成的介子表面束流线和TRIUMF的β衰变核磁共振设备来：1)研究不均匀性在高温超导机制中的作用，2)确定新发现的磁性在高温超导体重掺杂状态下的相关性，3)表征和优化利用氰金属酸盐构建块的一系列新型配位聚合物中的磁相互作用，4)通过涡旋状态的测量研究铁基超导体的配对对称性。5)研究磁通穿透对超导铌腔射频损耗的影响；6)研究金纳米结构的表面磁性。此外，我们将继续开发一种超极化氙气体核磁共振方法，作为一种非常灵敏的表面特性探针，有可能发现具有实际设备应用的新行为。

This proposal will primarily utilize newly constructed muon surface beam lines and the beta-decay NMR facility at TRIUMF to: 1) investigate the role inhomogeneity plays in the mechanism of high-temperature superconductivity, 2) determine the relevance of newly discovered magnetism in the heavily overdoped regime of high-temperature superconductors, 3) characterize and optimize magnetic interactions in a series of novel coordination polymers that make use of cyanometallate building blocks, 4) investigate the pairing symmetry of iron-based superconductors via measurements in the vortex state, 5) investigate the role of magnetic flux penetration in RF losses of superconducting Nb cavities used for charged-particle accelerators, and 6) investigate surface magnetism in gold nanostructures. In addition we will continue the development of a hyperpolarized xenon gas NMR method as an exquisitely senstive probe of surface properties with the potential to discover novel behaviour that has practical device applications. The muon spin rotation/relaxation (muSR) technique is unique in its ability to locally probe magnetism in materials, and for this purpose Canada has recently invested heavily in the construction and operation of new muon beam lines at TRIUMF. This proposal will exploit these new muSR capabilities as either the only means to collect information or to complement data obtained by other methods. Primary themes of this proposal include understanding the importance of nanoscale inhomogeneity on the development of a room-temperature superconductor, and controlled assembly of molecular building blocks in a predictable way as a means of designing a new generation of advanced magnetic materials.