Theoretical analysis of the double spin chain compound KCuCl_3

TL;DR

This paper provides a theoretical analysis of the magnetic and thermal properties of the double spin chain compound KCuCl_3 using an exactly solved ladder model, matching experimental data and identifying its phase as strongly dimerized.

Contribution

It introduces an exact solution approach to analyze KCuCl_3, accurately predicting critical fields and magnetic properties, advancing understanding of its quantum phase behavior.

Findings

Critical fields H_{c1}=22.74T and H_{c2}=51.34T predicted

Good agreement between theoretical and experimental susceptibility

Identified the compound as in a strong dimerized phase with a 35K energy gap

Abstract

We investigate thermal and magnetic properties of the double spin chain compound KCuCl_3 via an exactly solved ladder model with strong rung interaction. Results from the analysis of the thermodynamic Bethe Ansatz equations suggests the critical field values H_{c1}=22.74T and H_{c2}=51.34T, in good agreement with the experimental observations. The temperature dependent magnetic properties are directly evaluated from the exact free energy. Good overall agreement is seen between the theoretical and experimental susceptibility curves. Our results suggest that this compound lies in the strong dimerized phase with an energy gap $\Delta \approx 35$K at zero temperature.