Resonant two-magnon Raman scattering in two-dimensional and ladder-type Mott insulators

TL;DR

This paper studies resonant two-magnon Raman scattering in 2D and ladder Mott insulators using a Hubbard model, revealing different resonance behaviors linked to their distinct ground states.

Contribution

It demonstrates how the resonance behavior differs between 2D and ladder Mott insulators, explaining the role of their ground state properties.

Findings

Raman intensity in 2D is enhanced above the absorption edge.

In ladder systems, Raman intensity resonates with the absorption spectrum.

The ground state differences explain the contrasting resonance behaviors.

Abstract

We investigate the resonant two-magnon Raman scattering in the two-dimensional (2D) and ladder-type Mott insulators by using a half-filled Hubbard model in the strong coupling limit. By performing numerical diagonalization calculations for small clusters, we find that the model can reproduce the experimental features in the 2D that the Raman intensity is enhanced when the incoming photon energy is not near the absorption edge but well above it. In the ladder-type Mott insulators, the Raman intensity is found to resonate with absorption spectrum in contrast to the 2D system. The difference between 2D and the ladder systems is explained by taking into account the fact that the ground state in 2D is a spin-ordered state while that in ladder is a spin-gapped one.