Makoto Hashimoto (SIMES Seminar)

Date(s) - Jan 9 2015
11:00 AM - 12:00 PM

Shasta Room, Bldg. 40, Room 361




Phase competition between the pseudogap and superconductivity

Makoto Hashimoto

Staff Scientist, SLAC

 The spectral energy gap is an important signature that defines states of quantum matter: insulators, density waves and superconductors have very different gap structures. The unique momentum-resolved nature of angle-resolved photoemission spectroscopy (ARPES) makes it a powerful tool to characterize spectral gaps. In this talk, I will present our current understanding of spectral gaps in high-Tc cuprate superconductors, particularly focusing on the mysterious pseudogap, existing below the pseudogap temperature T*. I will show an antagonistic singularity at Tc in the spectral weight of Bi2Sr2CaCu2O8+δ as compelling evidence for phase competition, which has not been clearly identified in the spectral line shape. Comparison with theoretical calculations confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. Further, it shows how the pseudogap, superconductivity, and bosonic mode coupling contribute to the antinodal spectral lineshape that shows complex doping and temperature evolution. The competition at finite temperature, observed as the spectral weight singularity, persists up to a high hole concentration p ~ 0.22, provides new insights into the nature of the competitive interplay between the two intertwined orders and the complex phase diagram near the pseudogap critical point.