| Perovskite metal-oxides are known to exhibit rich physical properties, including high-temperature superconductivity, Mott- and band-insulating states, colossal magnetoresistance, multiferroic states and polaron physics. For this interest, angle-resolved photoemission studies (ARPES) have been successfully preformed in elucidating the electronic properties of doped Mott insulators, especially high-temperature cuprate superconductors. In this thesis, I will present ARPES study of single-layer Bi2Sr2CuO 6 superconductor.;The first part focuses on the dispersion anomaly ("kink") of single-layer Bi2Sr2CuO6 superconductor. The motivation comes from that the coupling of electrons to bosonic modes is known to be the heart of mechanism of Cooper pair formation in conventional superconductors. For cuprate superconductors, evidence of electron-boson coupling has manifested itself in the form of the dispersion anomaly. The self-energies obtained from the kink are compared between optimally doped and strongly overdoped, non-superconducting samples. Besides the appearance of a strong overall weakening, it is also found that the weight of self-energy in the overdoped system shifts to higher energies. Evidence shows that this could be related to a change in the coupling to c-axis phonons due to the rapid change of the c-axis screening in this doping range.;In the second part, at higher-energy scale, we present improved experimental data from four families of high-Tc superconductors, including Bi2Sr2CuO6, over a wide doping range that reveal a hierarchy of many-body interaction scales focused on: the low-energy anomaly (above) of 0.03--0.09 eV, a high-energy anomaly of 0.3--0.5 eV, and an anomalous enhancement of the width of the local-density-approximation-based CuO2 band extending to energies of ≈2 eV. Besides their universal behavior over the families, we find that all of these three dispersion anomalies also show clear doping dependence over the doping range presented. Further study shows that the essential features of high-energy-anomaly can be captured rather well by the calculation based on the single-band Hubbard model. |
