Red Bromide Research Articles

Nature of the magnetic interaction of Wurster's radicals in the solid state

The nature of the spin exchange interaction within the half-filled band in one-dimensional stacks of Wurster's radicals in Wurster's red bromide has been investigated theoretically. The various contributions to the Heisenberg effective exchange integral: direct, kinetic, and indirect spin exchange are evaluated quantitatively. It has been shown that the direct (Coulomb) exchange which causes the ferromagnetic coupling is small. The negative value of the effective exchange integral between Wannier functions, localized within the elementary units, has been determined by the kinetic and indirect (antiferromagnetic) exchange interaction.

The Magnetic Susceptibilities and ESR of Wurster’s Ions in Crystals

Abstract The magnetic susceptibilities and the electron spin resonances of Wurster’s blue bromide, blue iodide, and red bromide have been measured over a wide temperature range. The results show that the paramagnetism of Wurster’s blue bromide above 210°K and of iodide can be explained by the linear Ising model, consistent with the crystal structure. Wurster’s blue bromide showed a deviation from the linear Ising model below 210°K; the dimer model is most appropriate for the explanation of the experimental data. The intensities of the single ESR line are consistent with the results of the static susceptivility measurements. The hyperfine structures are not observed, perhaps because of the rapid movement of the triplet exciton. The magnetic results are explained in terms of the J-values, the origin of which are discussed on the basis of the interaction between the charge-transfer states and the singlet state. The values are resonably correlated with the interaction parameter, β, as estimated from the crystal structure and the electronic spectral measurements.

The crystal structure of Würster's red bromide

The crystal structure of Würster's red bromide