Structural and magnetic properties of spin-1/2 dimer compound Cu2(IPA)2(DMF)(H2O) with a large spin gap

Abstract

We present the synthesis and a detailed investigation of structural and magnetic properties of metal-organic compound Cu2(IPA)2(DMF)(H2O) by means of x-ray diffraction, magnetization, and heat capacity measurements. Single crystals of the title compound were synthesized by judicious selection of organic ligand and employing a selective hydrothermal reaction route. It crystallizes in an orthorhombic structure with space group Cmca. The structural analysis revealed that two Cu2+ ions are held together by the organic component (-O-C-O-) in a square paddle-wheel to form spin dimers which are aligned perpendicular to each other and are further coupled through organic ligands (isophthalic acid) forming two-dimensional layers. Temperature dependent magnetic susceptibility could be described well using spin-1/2 dimer model. The spin susceptibility shows an exponential decrease in the low temperature region, below the broad maximum, confirming the singlet ground state with a large spin gap of K. The heat capacity Cp measured as a function of temperature also confirms the absence of magnetic long-range-order down to 2 K.