Angle Resolved Photoemission Spectroscopy on High Temperature Superconductors

This thesis makes significant advances towards an understanding of superconductivity in the cuprate family of unconventional, high-temperature superconductors. Even though the high-temperature superconductors were discovered over 35 years ago, there is not yet a general consensus on an acceptable theory of superconductivity in these materials. One of the early proposals suggested that collective magnetic excitations of the conduction electrons could lead them to form pairs, which in turn condense to form the superconducting state at a critical temperature Tc. Quantitative calculations of Tc using experimental data were, however, not available to verify the applicability of this magnetic mechanism.

This book focuses on angle-resolved photoemission spectroscopy studies on novel interfacial phenomena in three typical two-dimensional material heterostructures: graphene/h-BN, twisted bilayer graphene, and topological insulator/high-temperature superconductors. Since the discovery of graphene, two-dimensional materials have proven to be quite a large “family”. As an alternative to searching for other family members with distinct properties, the combination of two-dimensional (2D) materials to construct heterostructures offers a new platform for achieving new quantum phenomena, exploring new physics, and designing new quantum devices.