Disrupted long-range spin-spiral ordering and electric polarization in the Zn-substituted quantum helimagnet LiCu_2-x Zn_xO₂

Long-range spin-spiral ordering in quantum quasi-two-dimensional helimagnet LiCu₂O₂ is destroyed by ∼8% Zn²⁺ substitution and a magnetic anomaly near ∼14 K of different character emerges. Zn substitution may have introduced either a magnetic ground state of spin glass in nature, antiferromagnetic ordering with complex easy-plane anisotropy, or a gapped phase which is phase separated and proportional to the Zn substitution level on a short-range ordered background. The magnetic ground state is modified at the same time that the electric polarization disappears.