Electronic structure of KTi(SO4)2.H2O - a S=1/2 frustrated chain antiferromagnet

TL;DR

This study uses electronic structure calculations and theoretical modeling to analyze the magnetic properties of KTi(SO4)2.H2O, revealing a higher frustration ratio than previously reported, and suggests experimental methods to clarify this discrepancy.

Contribution

The paper provides a microscopic magnetic model based on density functional theory and tight-binding calculations, challenging prior estimates of the frustration ratio in KTi(SO4)2.H2O.

Findings

Confirmed quasi-1D nature with antiferromagnetic J1 and J2

Found a larger frustration ratio alpha ~ 1.1

Suggested experimental measurements to resolve discrepancies

Abstract

The compound KTi(SO4)2.H2O was recently reported as a quasi one-dimensional spin 1/2 compound with competing antiferromagnetic nearest neighbor exchange J1 and next-nearest neighbor exchange J2 along the chain with a frustration ratio alpha = J2/J1 ~ 0.29 [Chem. Mater. vol. 20, pg. 8 (2008)]. Here, we report a microscopically based magnetic model for this compound derived from density functional electronic structure calculations along with respective tight-binding models. Our calculations confirm the quasi one-dimensional nature of the system with antiferromagnetic J1 and J2, but suggest a significantly larger frustration ratio alpha ~ 1.1 +- 0.2. Based on transfer matrix renormalization group calculations we found that, due to an intrinsic symmetry of the J1-J2 model, our larger frustration ratio alpha is also consistent with the previous thermodynamic data. To resolve this issue, we propose performing high-field magnetization measurements and low temperature susceptibility measurements which should allow to precisely identify the frustration ratio alpha.