Strong Field Induced Paramagnetic Anomaly in NiSiF6·6H2O

A non-Brillouin dependence of the magnetic moment ($M$) of nickel fluosilicate hexahydrate has been shown from experimental magnetization studies in the temperature ($T$) range 1.3-4.2°K and in magnetic fields ($H$) up to 58 000 gauss. A branching of magnetic moment isotherms, when $M$ is plotted against $\frac{H}{T}$, not only indicates non-Brillouin dependence but also eliminates the possibility of using simple exchange interaction to explain the results. The characteristic pattern of magnetic moment dependence on $\frac{H}{T}$ can be reproduced by the use of energy levels quadratic in the magnetic field, where the coefficient of the quadratic term is about 0.7×${10}^{-26\mathrm{}}$ erg ${\mathrm{gauss}}^{-2\mathrm{}}$.