On the Magnetism of Mn- and Co-Ammonium Tutton Salts at Very Low Temperatures

概要

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The parasitic ferromagnetism found in the ammonium tutton salt of Mn and Co ions is discussed. By assuming the two sublattice model, we look for the lowest energy state of spin direction, where the exchange and dipole interactions are taken into account. It can be shown that the origin of parasitic ferromagnetism in MnNH_4-tutton salt is the crystalline field and in CoNH_4-tutton salt the anisotropic dipolar and exchange interactions. The estimate of the angle with which the spins incline to the K_1K_2-plane are found to be 21°42' and 10°42' for Mn- and Co-NH_4-tutton salts respectively, agreeing well with the experhnental results, It appears theoretically that the spin direction for the lowest energy state lie within a plane which inclines to the K_1K_3-p1ane with angle -15°2' and -9°53' for Mn- and Co-tutton salts respectively. The Neel temperature and the susceptihilities are also calculated in rather good agreement with the measured values. It is noted that the directions corresponding to the maximum and minimum values of susceptibility within K_1K_2-plane deviate considerably from K_1- and K_2-axes.
社団法人日本物理学会の論文
1961-11-05