Dynamical Mean Field Theory of the Gutzwiller-projected BCS Hamiltonian: Phase Fluctuations and the Pseudogap

TL;DR

This paper develops a dynamical mean field theory for the Gutzwiller-projected d-wave BCS Hamiltonian, revealing two pseudogap energy scales and showing how on-site repulsion U renormalizes the superconducting gap, shedding light on phase fluctuations in high-Tc superconductors.

Contribution

It introduces a DMFT approach to the Gutzwiller-projected BCS Hamiltonian, connecting pseudogap phenomena with phase fluctuations and on-site interactions in high-temperature superconductivity.

Findings

Identification of two pseudogap energy scales related to pairing and phase coherence.

Strong renormalization of the superconducting gap due to on-site repulsive interaction U.

Connection of the model to the t-J and Heisenberg models at different doping levels.

Abstract

One of the most prominent problems in high temperature superconductivity is the nature of the pseudogap phase in underdoped regimes; particularly important is the role of phase fluctuations. The Gutzwiller-projected BCS Hamiltonian is a useful model for high temperature superconductivity due to an exact mapping to the Heisenberg model at half filling and generally a very close connection to the t-J model at moderate doping. We develop the dynamical mean field theory for the d-wave BCS Hamiltonian with on-site repulsive interaction, $U$, physically imposing the partial Gutzwiller projection. For results, two pseudogap energy scales are identified: one associated with the bare pairing gap for the singlet formation and the other with the local phase coherence. The real superconducting gap determined from sharp coherence peaks in the density of states shows strong renormalization from the bare value due to $U$.