Spin pseudogap in Ni-doped SrCuO2

TL;DR

This study reveals a pseudogap in Ni-doped SrCuO2 spin chains, showing it as a universal feature of quantum spin chains with dilute defects, supported by neutron scattering data and a simple theoretical model.

Contribution

It demonstrates the presence of a pseudogap in Ni-doped SrCuO2 and introduces a universal scaling model for quantum spin chains with dilute impurities.

Findings

Pseudogap of ~8 meV observed in Ni-doped SrCuO2

Pseudogap is not related to structural phase transitions

A simple model explains the experimental data across 2-300 K

Abstract

The S=1/2 spin chain material SrCuO2 doped with 1% S=1 Ni-impurities is studied by inelastic neutron scattering. At low temperatures, the spectrum shows a pseudogap \Delta ~ 8 meV, absent in the parent compound, and not related to any structural phase transition. The pseudogap is shown to be a generic feature of quantum spin chains with dilute defects. A simple model based on this idea quantitatively accounts for the exprimental data measured in the temperature range 2-300 K, and allows to represent the momentum-integrated dynamic structure factor in a universal scaling form.