Long-range antiferromagnetic order in the S=1 chain compound LiVGe2O6

The phase transition in the compound LiVGe2O6 has been proposed as a unique example of a spin-Peierls transition in an S=1 antiferromagnetic chain. We report neutron- and x-ray-diffraction measurements of LiVGe2O6 above and below the phase transition at T=24 K. No evidence is seen for any structural distortion associated with the transition. The neutron results indicate that the low-temperature state is antiferromagnetic, driven by ferromagnetic interchain couplings.