seminaire NFMQ ven. 26 mars 2021 14:30 - 16:30 (CET)

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Abstract :

Cuprate superconductors are one of the most enduring challenges in condensed matter physics. The numerous electronic orders that are observed in the pseudogap phase, before the system becomes a superconductor, makes finding a unifying theory a real challenge. We present here a recent idea [1] where the pseudogap phase is due to the fractionalization of modulated particle-particle pairs, a Pair Density Wave (PDW), into uniform particle-particle pairs, a superconducting (SC) order, and modulated particle-hole pairs, a Charge Density Wave (CDW). Similarly to the electron’s fractionalization, the PDW is given by the product of the SC and CDW orders to respect the symmetries. These two new orders are then linked by a constraint which is at the origin of the pseudogap phenomenology.
We develop an effective theory based on the two orders mentioned earlier leading to two phase transitions, the first one being the opening of the pseudogap while the second one is the usual superconducting transition [1]. As soon as we enter the pseudogap phase, amplitudes and phases of the SC and CDW orders are constrained. This phase locking is directly related to some intriguing observations of phase coherence of the CDW order inside superconducting vortices by STM [2]. On the other hand, we show, starting from a microscopic model, that the pseudogap phase presents Fermi arcs as observed by ARPES. We also give a detailed comparison of the energy and temperature dependence of the electronic  spectral function with experiments and with numerical DMFT calculations. [3,4,5].

References :
[1] D. Chakraborty et al., Phys. Rev. B 100, 224511 (2019).
[2] M. H. Hamidian et al., arXiv:1508.00620,
[3] M. Grandadam et al., Phys. Rev. B 102, 121104 (2020)
[4] R.-H. He et al., Science 331, 1579 (2011).
[5] M. Grandadam et al., arXiv:2012.11226