Model for the neutron resonance in HgBa2CuO4+δ

Abstract

We study the spin dynamics of the resonant excitonic state (RES) proposed, within the theory of an emergent SU(2) symmetry, to explain some properties of the pseudogap phase of cuprate superconductors. The RES can be described as a proliferation of particle-hole patches with an internal modulated structure. We model the RES modes as a charge order with multiple $2{\mathbf{p}}_{\text{F}}$ ordering vectors, where $2{\mathbf{p}}_{\text{F}}$ connects two opposite sides of the Fermi surface. This simple modelization enables us to propose a comprehensive study of the collective mode observed at the antiferromagnetic wave vector $\mathbf{Q}=(\ensuremath{\pi},\ensuremath{\pi})$ by inelastic neutron scattering in both the superconducting state and also in the pseudogap regime. In this regime, we show that the dynamic spin susceptibility exhibits a loss of coherence terms except at special wave vectors commensurate with the lattice. We argue that this phenomenon could explain the change of the spin response shape around $\mathbf{Q}$. We demonstrate that the hole dependence of the RES spin dynamics is in agreement with the experimental data in ${\mathrm{HgBa}}_{2}{\mathrm{CuO}}_{4+\ensuremath{\delta}}$.