Gutzwiller Magnetic Phase Diagram of the Undoped t-t'-U Hubbard Model

TL;DR

This paper maps the magnetic phase diagram of the half-filled t-t'-U Hubbard model using Gutzwiller RPA, revealing incommensurate phases, their stability, and implications for cuprate physics.

Contribution

It provides a detailed analysis of magnetic phases in the Hubbard model, highlighting the role of incommensurate phases and their stability, using an advanced approximation method.

Findings

Incommensurate phases emerge as U increases.

Crossover from incommensurate to commensurate phases occurs with gap opening.

Double occupancy remains mildly suppressed in the absence of magnetic order.

Abstract

We calculate the magnetic phase diagram of the half-filled t-t'-U Hubbard model as a function of t' and U, within the Gutzwiller approximation RPA (GA+RPA). As U increases, the system first crosses over to one of a wide variety of incommensurate phases, whose origin is clarified in terms of double nesting. We evaluate the stability regime of the incommensurate phases by allowing for symmetry-breaking with regard to the formation of spin spirals, and find a crossover to commensurate phases as U increases and a full gap opens. The results are compared with a variety of other recent calculations, and in general good agreement is found. For parameters appropriate to the cuprates, double occupancy should be only mildly suppressed in the absence of magnetic order, inconsistent with a strong coupling scenario.