On the high energy spin excitations in the high temperature superconductors: an RVB theory

TL;DR

This paper uses an RVB theory to analyze high energy spin excitations in high T_c cuprates, deriving a mode dispersion that matches experimental RIXS data and showing doping independence of certain spectral features.

Contribution

It provides an exact mode dispersion formula within the RVB framework and demonstrates its consistency with experimental observations of spin excitations in cuprates.

Findings

Mode dispersion of about 2.2J along the a0 to M line.

Doping independence of mode energy and spectral intensity.

Agreement with recent RIXS measurements.

Abstract

The high energy spin excitation in the high T$_{c}$ cuprates is studied in the single mode approximation for the $t-t'-J$ model. An exact form for the mode dispersion is derived. When the Gutzwiller projected BCS state is used as the variational ground state, a spin-wave-like dispersion of about 2.2$J$ is uncovered along the $\Gamma=(0,0)$ to $\mathrm{M}=(\pi,0)$ line. Both the mode energy and the integrated intensity of the spin fluctuation spectrum are found to be almost doping independent in large doping range, which agrees very well with the observations of recent RIXS measurements. Together with previous studies on the quasiparticle properties of the Gutzwiiler projected BCS state, our results indicate that such a Fermionic RVB theory can provide a consistent description of both the itinerant and the local aspect of electronic excitations in the high T$_{c}$ cuprates.