Quasi-two-dimensional magnetism in spin- square lattice compound Cu[C₆H₂(COO)₄][H₃N-(CH₂)₂-NH₃] · 3H₂O

Abstract

We report the crystal growth and structural and magnetic properties of quasi-two-dimensional quantum magnet Cu[C6H2(COO)4][H3N-(CH2)2-NH3] 3H2O. It is found to crystallize in a monoclinic structure with space group . The CuO4 plaquettes are connected into a two-dimensional framework in the ab-plane through the anions of [C6H2(COO)4]4− (pyromellitic acid). The [H3N-(CH2)2-NH3] 3H2O groups are located between the layers and provide a weak interlayer connection via hydrogen (H...O) bonds. The temperature-dependent magnetic susceptibility is well described by frustrated square lattice model with nearest-neighbor interaction and next-nearest-neighbor interaction . Our analysis using frustrated rectangular lattice model also confirms almost isotropic nearest-neighbour interactions ( and ) in the ab-plane and . Further, the isothermal magnetization at is also well described by a non-frustrated square lattice model with . Based on the ratio, the compound can be placed in the Néel antiferromagnetic state of the phase diagram. No signature of magnetic long-range order is detected down to 2 K.