Competing orders in low dimensional organic superconductors

点击翻译按钮获取中文摘要

This research program will be mainly focused on the development and application of theoretical tools grounded on the weak coupling renormalization group (RG) theory, a plan essentially stimulated by experiments that are carried out on quasi-one-dimensional organic superconductors. In spite of their complex molecular structure, these correlated systems stand out as a paradigm of simplicity to exhibit a close proximity between antiferromagnetism and unconventional superconductivity. We shall exploit the aptness of the RG method to study the nature of quantum criticality associated with superconductivity in the close vicinity of a magnetic spin-density wave phase in the Pressure-Temperature phase diagram of such materials. The RG method will be extended to high order to investigate the collective excitations surrounding quantum criticality and their influence on quasi-particles states of the metallic phase that precedes superconductivity. Particular emphasis will be put on the nature of quasi-particle excitations, their spectral features that enter in the behavior of transport quantities, whose observed anomalous behaviors have remained an enduring question since their discovery in unconventional superconductors including pnictides, cuprates and heavy-fermion systems. We intend to further develop the RG method for models of retarded electron-boson interactions. Electron-phonon coupling is actually relevant for another paradigm of quantum criticality, which brings into interplay a charge-density-wave state with superconductivity in the phase diagram of some classes of quasi-1D organics and inorganics under pressure. We shall investigate the role of retardation in interactions for the onset of quantum criticality and the impact of competing orders on the nature of quasi-particle excitations in the metallic state. Finally, we shall go along with extending the RG method to lattice 1D and quasi-1D models of interacting electrons instead of the usual continuum approach, which fails in several documented occasions to capture either the correct physics of correlations at long distance or the correct spectral properties at finite energy.