Magnetic incommensurability in $p$-type cuprate perovskites

TL;DR

This paper models the magnetic susceptibility in p-type cuprates using the t-J model, explaining incommensurate magnetic responses and hourglass dispersion without charge modulation or nesting, aligning well with experimental observations.

Contribution

It introduces a theoretical approach that reproduces key magnetic features in cuprates without relying on charge stripe or nesting mechanisms.

Findings

Incommensurate magnetic response can arise from decay of hole peaks.

Hourglass dispersion pattern matches experimental data.

Resonance peak intensity depends on excitation energy relative to the fermion continuum.

Abstract

For the superconducting phase with a d-wave order parameter and zero temperature the magnetic susceptibility of the t-J model is calculated using the Mori projection operator technique. Conditions for the appearance of an incommensurate magnetic response below the resonance frequency are identified. A fast decay of the tails of the hole coherent peaks and a weak intensity of the hole incoherent continuum near the Fermi level are enough to produce an incommensurate response using different hole dispersions established for $p$-type cuprates, in which such response was observed. In this case, the nesting of the itinerant-electron theory or the charge modulation of the stripe theory is unnecessary for the incommensurability. The theory reproduces the hourglass dispersion of the susceptibility maxima with their location in the momentum space similar to that observed experimentally. The upper branch of the dispersion stems from the excitations of localized spins, while the lower one is due to the incommensurate maxima of their damping. The narrow and intensive resonance peak arises if the frequency of these excitations at the antiferromagnetic momentum lies below the edge of the two-fermion continuum; otherwise the maximum is broad and less intensive.