Biquadratic interactions and spin-Peierls transition in the spin 1 chain LiVGe2O6

TL;DR

This paper reports on the discovery of a spin-Peierls transition in LiVGe2O6, a new S=1 chain system, driven by significant biquadratic interactions, supported by experimental susceptibility measurements and quantum chemistry calculations.

Contribution

It introduces LiVGe2O6 as a new S=1 chain exhibiting a spin-Peierls transition due to biquadratic interactions, which is a novel finding in this class of materials.

Findings

Abrupt susceptibility drop at 22 K indicating a spin-Peierls transition

Presence of a gapless spectrum above the transition temperature

Quantum chemistry calculations support significant biquadratic exchange interactions

Abstract

The magnetic susceptibility of a new one-dimensional, S=1 system, the vanadium oxide LiVGe2O6, has been measured. Contrary to previous S=1 chains, it exhibits an abrupt drop at 22 K typical of a spin-Peierls transition, and it is consistent with a gapless spectrum above this temperature. We propose that this behaviour is due to the presence of a significant biquadratic exchange interaction, a suggestion supported by quantum chemistry calculations that take into account the quasi-degeneracy of the t2g levels.