Detail:
Abstract: 100 years into the discovery of superconductivity, only a handful of materials demonstrate Tc's above the empirical electron-phonon McMillan limit - the H3S under pressure, the iron-based single crystal superconductor, the mono-layer FeSe/STO and the high Tc cuprate superconductors. While ultrahigh vacuum (FeSe/STO) and high pressure (H3S) impose intrinsic limitations for a comprehensive investigation, the superconductivity in cuprates at it prime remains largely intertwined with other competing orders. Here we report the first spectroscopic evidence for a pure d-wave superconductivity in extremely overdoped Bi2212 with Tc of 49K. The momentum structure, particle-hole symmetry and condensation energy of the superconductivity are thoroughly investigated within BCS framework via angle-resolved photoemission spectroscopy (ARPES). No Lifshitz transition happens up to 24% hole doping, and the superconducting coupling constant is reduced to a BCS strong coupling regime. A new laser light source will be introduced at the end to address this BSCCO system with high precision and consistency. Biosketch: Yu He graduated from the class of 0600 of USTC with bachelor's degree of physics in 2010, working on the interaction between superconductivity and magnetism in iron pnictide with Prof. Xianhui Chen. He then joined the photoemission group of Prof. Zhi-Xun Shen at Stanford University to work on copper-based high temperature superconductors. His current research focus mainly includes the polaronic excitation and Mottness in (La,Sr)2CuO4 system, the mode coupling and the gap symmetry in Bi-2212 system. He also led the effort in the development of the next generation tabletop VUV laser light source.
