Helimagnetism and weak ferromagnetism in NaCu₂O₂and related frustrated chain cuprates

Abstract

A novel subclass of frustrated undoped edge-shared CuO2 chain materials with intriguing magnetism is briefly reviewed. These cuprates show at low temperature a tendency to helicoidal magnetic ordering with acute pitches and in some cases also to weak ferromagnetism. In our analysis we focus on our recent theoretical and experimental studies on Na(Li)Cu2O2 and related systems. Differences and similarities in the magnetic ground states of these structurally similar localized spin-1/2 compounds are considered. The nontrivial interplay of frustrated single-chain couplings, anisotropy and interchain exchange is stressed.