Non-equilibrium study of the phase diagram of cuprates

The phase diagram of cuprates hosts numerous intertwined phases, such as high-temperature superconductivity, charge order and the pseudogap phenomenon. This makes the precise description of each separate phase challenging. In particular, thermal excitations govern the appearance of different phases and thermodynamic phase transitions. We recently demonstrated the capability to study the superconductor-to-normal state transition in Bi₂Sr₂CaCu₂O_8+δ cuprate superconductor in an ultrafast fashion. In particular, we demonstrated that time-resolved photoemission spectroscopy can disentangle the dynamics of phase fluctuations and charge excitation, establishing the dominant role of phase coherence in the emergence of high-temperature superconductivity [1]. In the same line of thought, we applied this non-equilibrium approach to (i) reveal the transient competition between charge-order and superconducting phases and (ii) explain the enhanced electron-boson band renormalization (kink) in terms of the opening of the superconducting gap and pseudogap.

[1] Boschini et al., Nature Materials 17, 416-420 (2018)