Phases of the 2D Hubbard model at low doping

TL;DR

This paper investigates the low doping phases of the 2D Hubbard model, revealing a new noncoplanar spin state with incommensurate order, relevant to experimental observations in cuprate superconductors.

Contribution

It introduces a novel noncoplanar spin configuration at low doping, extending understanding of magnetic phases in the 2D Hubbard model.

Findings

The spiral phase is unstable towards a noncoplanar state.

The new state has incommensurate order with inverse pitch proportional to x^(1/2).

Susceptibility peaks at (,) are consistent with experimental data.

Abstract

We show that the planar spiral phase of the 2D Hubbard model at low doping, x, is unstable towards a noncoplanar spin configuration. The novel equilibrium state we found at low doping is incommensurate with the inverse pitch of the spiral varying as x^(1/2), but nevertheless has a dominant peak in the susceptibility at (\pi,\pi). Relevance to the NMR and neutron scattering experiments in La_2-xSr_xCuO_4 is disccussed.