抄録
Proton NMR of an approximate magnetic sandwich system Co(HCOO)2·2H2O is investigated. From the analysis of angular dependence of the resonance frequency, we determine all the components of paramagnetic sublattice susceptibility tensors and of spontaneous sublattice magnetizations which can not be obtained by the other experiments such as susceptibility, magnetization or torque measurement. These sublattice magnetizations show that exchange interactions in A plane and between A and B planes are antiferro- and ferromagnetic, respectively.
The temperature dependence of spontaneous staggered magnetizations LA0 and LB0 on A and B planes is obtained from that of the resonance frequency. The results |LA0|∝εβ(β=0.13±0.01) and |LB0|∝|LA0|⁄T seem to indicate that the sandwiched paramagnetic ions do not participate cooperatively in the phase transition at TN with the ions on A plane.
