Reply to Comment on ‘Oxygen vacancy-induced magnetic moment in edge-sharing CuO2 chains of Li2CuO2-δ’

Abstract

In this reply to the comment on ‘Oxygen vacancy-induced magnetic moment in edge-sharing CuO _2 chains of ${{\rm{Li}}}_{2}{{\rm{CuO}}}_{2-\delta }$ ’ (2017 New Journal of Physics 19 023206), we have clarified several key questions and conflicting results regarding the size of the intra-chain nearest neighbor coupling J _1 and the sign of the Weiss temperature Θ defined in the Curie–Weiss law of χ (T) = χ _◦ + C/(T − Θ). Additional data analysis is conducted to verify the validity of the Curie–Weiss law fitting protocol, including the negative sign and size of Θ based on the high-temperature linear temperature dependence of 1/ χ (T) for T > J _1 and $\tfrac{g{\mu }_{B}{SH}}{{k}_{B}T}\ll 1$ . The consistency between the magnetic antiferromagnetic (AF) ground state below T _N and the negative sign of Θ in the high-temperature paramagnetic (PM) state is explained via the reduction of thermal fluctuation for a temperature-independent local field due to magnetic interaction of quantum nature. A magnetic dipole–dipole (MDD)-type interaction among FM chains is identified and proposed to be necessary for the 3D AF magnetic ground state formation, i.e., the Heisenberg model of an exchange-type interaction alone is not sufficient to fully describe the quasi-1D spin chain system of ${{\rm{Li}}}_{2}{{\rm{CuO}}}_{2}$ . Several typical quasi-1D spin chain compounds, including ${{\rm{Li}}}_{2}{{\rm{CuO}}}_{2},{{\rm{CuAs}}}_{2}{{\rm{O}}}_{4},{{\rm{Sr}}}_{3}{{\rm{Fe}}}_{2}{{\rm{O}}}_{5}$ , and CuGeO _3 , are compared to show why different magnetic ground states are achieved from the chemical bond perspective.

Keywords

• spin chain
• magnetic susceptibility
• Curie–Weiss law
• exchange coupling
• Heisenberg model
• oxygen vacancy