Fermionic spinon theory of the hourglass spin excitation spectrum of the cuprates

TL;DR

This paper develops a fermionic spinon theory to explain the hourglass-shaped spin excitation spectrum observed in hole-doped cuprates, linking stripe order, fractionalized Fermi liquids, and neutron scattering data.

Contribution

It introduces a novel fermionic spinon framework that captures the hourglass spectrum and its evolution with stripe order in cuprates, connecting experimental observations with theoretical models.

Findings

Reproduces the hourglass spectrum near stripe-ordering wavevector

Predicts additional scattering features at higher energies and different Brillouin zone locations

Links fractionalized Fermi liquid behavior with spin excitation spectra in cuprates

Abstract

We present a theory for the spin fluctuation spectrum of the hole-doped cuprates in a ground state with period 4 unidirectional charge density wave (`stripe') order. Motivated by recent experimental evidence for a fractionalized Fermi liquid (FL*) description of the intermediate temperature pseudogap metal, we employ a theory of fermionic spinons which are confined with the onset of stripe order at low temperatures. The theory produces the `hourglass' spectrum near stripe-ordering wavevector observed by neutron scattering. Additional scattering from spinon continua and bound states appears at higher energies and elsewhere in the Brillouin zone, and could be observed by neutron or X-ray scattering.