Quantum Spin Systems: From Spin Gaps to Pseudo Gaps

TL;DR

This paper investigates the spin excitation spectra of low-dimensional quantum spin systems, exploring their gapped and pseudo-gapped states, and relates these findings to phenomena like superconductivity and charge ordering.

Contribution

It provides spectroscopic characterization of various low-dimensional spin systems considering interactions like spin-phonon coupling and charge ordering, linking to high-temperature superconductor pseudo gaps.

Findings

Identification of spin gaps and bound states in low-dimensional systems

Correlation between spin excitations and pseudo gaps in superconductors

Insights into the effects of doping and charge ordering on spin spectra

Abstract

Many low dimensional spin systems with a dimerized or ladder-like antiferromagnetic exchange coupling have a gapped excitation spectrum with magnetic bound states within the spin gap. For spin ladders with an even number of legs the existence of spin gaps and within the t-J model a tendency toward superconductivity with d-wave symmetry is predicted. In the following we will characterize the spin excitation spectra of different low dimensional spin systems taking into account strong spin phonon interaction ($\rm CuGeO_3$), charge ordering ($\rm NaV_2O_5$) and doping on chains and ladders (\ladder). The spectroscopic characterization of the model systems mentioned above has been performed using magnetic inelastic light scattering originating from a spin conserving exchange scattering mechanism. This is also bound to yield more insight into the interrelation between these spin gap excitations and the origin of the pseudo gap in high temperature superconductors.