On the magnetic structure of quasi one dimensional spin 1/2 system of Li2ZrCuO4

Magnetization and Li-7-NMR measurements have been carried out for an a-axis-aligned sample of Li2ZrCuO4, which has quasi one-dimensional Cu2+ spins (s = 1/2) in chains of edge-sharing CuO4 square planes and exhibits the magnetic transition at temperature T-N similar to 7 K. The NMR results at similar to 2 K indicate that the system has an incommensurate helical order of Cu spins within the ac-plane. Although the feroelectricity is predicted in this ordered state by existing theories developed for a single chain, no anomalies have been observed in the dielectric susceptibility E and electric polarization P for polycrystalline samples.