Photoemission in the strange metal region of Bi2212*

In the study of cuprate high temperature superconductors, it remains a major task to understand the strange metal region above the pseudogap temperature. Angle-resolved photoemission spectroscopy (ARPES), a powerful surface-sensitive probe of electronic structure, becomes challenging in this region due to the worsened vacuum condition at high temperature. Using improved experimental setup, we perform high-precision ARPES measurements on Bi2212 deep in the strange metal region while free from sample aging. We will present the doping and temperature evolutions of spectral coherence in this region, and discuss the implication of our results on the generic phase diagram of high temperature superconductors.