Visualizing the Interplay of Structural and Electronic Disorders in High-Temperature Superconductors using Scanning Tunneling Microscopy

The discovery of high-$T_c$ superconductivity in 1986 generated tremendous excitement. However, despite over 25 years of intense research efforts, many properties of these complex materials are still poorly understood. For example, the cuprate phase diagram is dominated by a mysterious ``pseudogap'' state, a depletion in the Fermi level density of states which persists above the superconducting critical temperature $T_c$. Furthermore, these materials are typically electronically inhomogeneous at the atomic scale, but to what extent the intrinsic chemical or structural disorder is responsible for electronic inhomogeneity, and whether the inhomogeneity is relevant to pseudogap or superconductivity, are unresolved questions. In this thesis, I will describe scanning tunneling microscopy experiments which probe the interplay of structural, chemical and electronic disorder in high-$T_c$ superconductors.