Magnetic properties of honeycomb spin lattice compounds Na2M2TeO6 (M = Co, Ni) and spin dimer compound Na2Cu2TeO6 single crystals by flux-growth

Abstract

We report the single crystal growth, structural and magnetic properties of honeycomb spin-lattice compounds Na 2 M 2 TeO 6 (M = Co, Ni) and spin dimer compound Na 2 Cu 2 TeO 6 . The single crystals of Na 2 M 2 TeO 6 (M = Co, Ni, Cu) have been grown by the self-flux method, which is one of the good techniques to control the magnetic impurity, different crystalline phase, crystal morphology, crystal size and the crystal surface through the selection of a suitable self-flux. Crystal structure, magnetic and thermodynamics properties are examined using X-ray diffraction (XRD), magnetic susceptibility and heat capacity measurements, respectively. The single crystal XRD studies of Na 2 M 2 TeO 6 (M = Co, Ni, Cu) show the purity and the high quality of grown single crystals. The measurements of magnetic susceptibility of Na 2 M 2 TeO 6 show the distinct anisotropic behaviour of the prepared single crystals. The anisotropic behaviour and the complicated magnetic phase transitions observed arise from the distinct honeycomb planes constituted by MO 6 octahedra in Na 2 M 2 TeO 6 (M = Co, Ni) leading to the antiferromagnetic (AFM) interaction in the honeycomb planes. In the case of Na 2 Cu 2 TeO 6 broad maximum occurring at 160 K is believed to arise from short-range one-dimensional antiferromagnetic correlations. The values of (effective magnetic moment) μ eff. observed for Na 2 Co 2 TeO 6 , Na 2 Ni 2 TeO 6 and Na 2 Cu 2 TeO 6 are 5.42 μ B , 3.17 μ B and 1.96 μ B respectively.