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

TL;DR

This study uses quantum Monte Carlo simulations to demonstrate how quantum magnetic fluctuations can induce pseudogap behavior and precursor pairing in a non-Fermi liquid, shedding light on high-temperature superconductor phenomena.

Contribution

It provides the first lattice model evidence that pseudogap states can emerge from pairing fluctuations driven by quantum critical magnetic fluctuations.

Findings

Observation of enhanced pairing fluctuations and partial gap opening.

Identification of a 'gap-filling' behavior in the pseudogap regime.

System remains non-superconducting until much lower temperatures.

Abstract

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, consistent with experimental observations. Our results provide the first unambiguous lattice model realization of a pseudogap state in a strongly correlated system, driven by superconducting fluctuations.