ALTERNATING EXCHANGE IN FERRIMAGNETIC ISING CHAINS

We propose a general treatment for solving J-alternating ferrimagnetic Ising chains, made up of two spin sublattices (s, S). Exact expressions of the susceptibility are derived for s = 1/2 spins alternating with arbitrary S quantum spins, including a local anisotropy on the second sublattice, Db. The magnetic properties of the ordered bimetallic chain MnCo (EDTA), 6H2O is discussed on the basis of the developed model

Crystal structure and magnetism of Co(HPO3)⋅H2O : A novel layered compound of Co(II)

The crystal structure and magnetic properties of Co(HPO3)⋅H2O have been determined. The solid crystallizes in space group Pca21, a=8.984(2) Å, b=7.918(2) Å, c=10.139(8) Å, V=721.2 Å3. Z=4 dcalc =2.89 g/cm3. The structure consists of layers only connected by hydrogen bonds. These layers can be viewed as formed by zigzag chains of edge‐sharing Co(II)O6 octahedra interconnected by a three atom bridge (O‐P‐O) and a single oxygen bridge. ac magnetic susceptibility measurements show a sharp peak at Tc =(10.8±0.1) K, and are consistent with a transition from one‐ to two‐dimensional magnetic order, in agreement with the structure. An analysis of the χT/C vs ϵ=(1−Tc/T) data in the critical region, for T>Tc, using a double‐logarithmic plot, yields a critical exponent γ=1.75 for 0.01<ϵ<0.1, which correspond to a two‐dimensional Ising [email protected] ; [email protected] ; [email protected]