New pyrochlore-like compound Cu₂OCl₂ with S = 1/2

We report here on the magnetic properties of Cu₂OCl₂, the structure of which can be regarded either as a pyrochlore-like corner-shared tetrahedral network with S = 1/2 or cross-linking chains of edge-sharing CuO₂Cl₂ squares. The magnetic susceptibility exhibits a broad maximum at approximately 140 K, indicating a low-dimensional feature, and drops at 70 K accompanied with a small specific-heat jump; however, it does not follow the typical S = 1/2 linear chain model. The magnetic susceptibility can be explained by a mean field corrected chain model with a closed value of the intra- and interchain exchange constants; thus, magnetic frustration would be dominant over a low-dimensional feature in Cu ₂OCl₂. From the band calculation results, we found that the Cu 3d on-site Coulomb interaction is essential to describe the electronic structure of Cu₂OCl₂. We conclude that Cu ₂OCl₂ should be regarded as a 3D material that has the potential to combine the pyrochlore-like geometrical frustration and the strong correlation among the Cu 3d electrons.