Saturation Field of Frustrated Chain Cuprates: Broad Regions of Predominant Interchain Coupling

Abstract

A thermodynamic method to extract the interchain coupling (IC) of spatially anisotropic 2D or 3D spin-1/2 systems from their empirical saturation field H_s (T=0) is proposed. Using modern theoretical methods we study how H_s is affected by an antiferromagnetic (AFM) IC between frustrated chains described in the J₁-J₂-spin model with ferromagnetic 1st and AFM 2nd neighbor in-chain exchange. A complex 3D-phase diagram has been found. For Li₂CuO₂ and Ca₂Y₂Cu₅O₁₀, we show that H_s is solely determined by the IC and predict H_s≈61 T for the latter. With H_s≈55 T from magnetization data one reads out a weak IC for Li₂CuO₂ close to that obtained from inelastic neutron scattering.