Crystal growth and magnetic ordering of Na2Ni2TeO6 with honeycomb layers and Na2Cu2TeO6 with Cu spin dimers
Abstract
We report on the crystal growth and magnetic property studies of layered Na2Ni2TeO6 and Na2Cu2TeO6. The former has a honeycomb layer composed of NiO6 octahedra and the latter is composed of paired CuO4 plaquettes connected through TeO6 octahedra. The 3D antiferromagnetic (AF) phase transition is defined with the peak of dχ/dT at ~27 K for Na2Ni2TeO6 and confirmed with specific heat measurement. A comparison is made between the magnetic behavior of Na2Ni2TeO6 and BaNi2V2O8, with a similar Ni honeycomb network of different centers. Na2Cu2TeO6 has been confirmed to have a spin gap of Δ/kB ~ 262 K due to spin dimerization of Cu2+S = 1/2 within each paired CuO4 plaquette.