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Abstract:
Magnetic susceptibility measurements and a microscopic magnetic model of the mineral clinoclase Cu-3(AsO4)(OH)(3) are reported. This spin-1/2 material can be well described as a combination of two nonequivalent spin dimers with the sizable magnetic couplings of J similar or equal to 700 K and J(D2) similar or equal to 300 K but only small interdimer couplings. Based on density functional theory calculations, we pinpoint the location of dimers in the rather complex crystal structure. Counterintuitively, the largest exchange coupling operates between the structural Cu2O6 dimers. Additionally, we investigate magnetostructural correlations in Cu2O6 structural dimers by considering the influence of the hydrogen position on the magnetic coupling. To evaluate accurate exchange couplings, we establish the hydrogen positions that were not known so far and analyze the pattern of hydrogen bonding.
