Scaling of dynamic spin correlations in BaCu2SiGeO7

TL;DR

This study investigates the dynamic spin correlations in BaCu2SiGeO7, confirming Luttinger liquid behavior at certain energies and revealing a breakdown of scaling at higher energies due to lattice effects.

Contribution

It provides the first comprehensive analysis of the energy and temperature dependence of spin correlations in BaCu2SiGeO7, clarifying previous misconceptions and extending understanding of one-dimensional quantum spin systems.

Findings

Scaling consistent with Luttinger spin liquid at 0.5-25 meV

Breakdown of scaling laws at higher energies due to lattice effects

Results align with behaviors observed in similar S=1/2-chain compounds

Abstract

The magnetic dynamic structure factor of the one-dimensional S = 1/2 chain system BaCu2(Si0.5Ge0.5)2O7 is studied in a wide range of energy transfers and temperatures. Contrary to previous erroneous reports [T. Masuda et al., Phys. Rev. Lett. 93, 077206 (2004)], the scaling properties observed in the range 0.5-25 meV are found to be fully consistent with expectations for a Luttinger spin liquid. At higher energies, a breakdown of scaling laws is observed and attributed to lattice effects. The results are complementary to those found in literature for other S = 1/2-chain compounds, such as KCuF3 and Cu-benzoate.