Influence of higher d-wave gap harmonics on the dynamical magnetic susceptibility of high-temperature superconductors

TL;DR

This study investigates how higher d-wave gap harmonics influence the magnetic susceptibility in high-temperature superconductors, revealing their role in lowering the spin gap and affecting incommensurate peak behavior observed in neutron scattering experiments.

Contribution

It demonstrates that higher d-wave harmonics significantly impact the magnetic susceptibility and incommensurate peaks in high-Tc superconductors, based on fermiology calculations aligned with ARPES data.

Findings

Higher d-wave harmonics lower the spin gap at incommensurate peaks.

The crossover from parallel to diagonal incommensuration is linked to minima in the 2-particle energy continuum.

The effects are robust across different fermiology models.

Abstract

Using a fermiology approach to the computation of the magnetic susceptibility measured by neutron scattering in hole-doped high-Tc superconductors, we estimate the effects on the incommensurate peaks caused by higher d-wave harmonics of the superconducting order parameter induced by underdoping. The input parameters for the Fermi surface and d-wave gap are taken directly from angle resolved photoemission (ARPES) experiments on Bi{2}Sr{2}CaCu{2}O{8+x} (Bi2212). We find that higher d-wave harmonics lower the momentum dependent spin gap at the incommensurate peaks as measured by the lowest spectral edge of the imaginary part in the frequency dependence of the magnetic susceptibility of Bi2212. This effect is robust whenever the fermiology approach captures the physics of high-Tc superconductors. At energies above the resonance we observe diagonal incommensurate peaks. We show that the crossover from parallel incommensuration below the resonance energy to diagonal incommensuration above it is connected to the values and the degeneracies of the minima of the 2-particle energy continuum.