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 ${J}_{1}\mathrm{\text{\ensuremath{-}}}{J}_{2}$-spin model with ferromagnetic 1st and AFM 2nd neighbor in-chain exchange. A complex 3D-phase diagram has been found. For ${\mathrm{Li}}_{2}{\mathrm{CuO}}_{2}$ and ${\mathrm{Ca}}_{2}{\mathrm{Y}}_{2}{\mathrm{Cu}}_{5}{\mathrm{O}}_{10}$, we show that ${H}_{s}$ is solely determined by the IC and predict ${H}_{s}\ensuremath{\approx}61\text{ }\text{ }\mathrm{T}$ for the latter. With ${H}_{s}\ensuremath{\approx}55\text{ }\text{ }\mathrm{T}$ from magnetization data one reads out a weak IC for ${\mathrm{Li}}_{2}{\mathrm{CuO}}_{2}$ close to that obtained from inelastic neutron scattering.