Monte Carlo study of the pseudogap and superconductivity emerging from quantum magnetic fluctuations

The origin of pseudogap in high-T-c superconductors remains a big puzzle. Here, the authors report numerical evidence of pseudogap behavior employing Quantum Monte Carlo algorithm emerging from pairing fluctuations in a quantum-critical non-Fermi liquid, similar to the pseudogap phase observed in cuprate superconductors. The origin of the pseudogap behavior, found in many high-T-c superconductors, remains one of the greatest puzzles in condensed matter physics. One possible mechanism is fermionic incoherence, which near a quantum critical point allows pair formation but suppresses superconductivity. Employing quantum Monte Carlo simulations of a model of itinerant fermions coupled to ferromagnetic spin fluctuations, represented by a quantum rotor, we report numerical evidence of pseudogap behavior, emerging from pairing fluctuations in a quantum-critical non-Fermi liquid. Specifically, we observe enhanced pairing fluctuations and a partial gap opening in the fermionic spectrum. However, the system remains non-superconducting until reaching a much lower temperature. In the pseudogap regime the system displays a gap-filling rather than gap-closing behavior, similar to the one observed in cuprate superconductors. Our results present direct evidence of the pseudogap state, driven by superconducting fluctuations.

Automated summary

The origin of the pseudogap in high-Tc superconductors remains a puzzle. Using numerical simulations, the authors find that it arises from pairing fluctuations in a quantum-critical non-Fermi liquid, similar to the pseudogap phase observed in cuprate superconductors. This finding provides direct evidence for the formation of the pseudogap state.