Temperature-induced changes in physical properties and lattice symmetry of nickel crystals

It has been shown that the changes in some physical properties of nickel crystals can be explained on the assumption of the existence of an isotropic magnetic phase within the temperature range 470 < T < 631 K, whose thermodynamic properties are determined by the exchange interaction alone. At T _is ≈ 470 K, this phase should be transformed into an anisotropic magnetic phase because of the cooperative effect of relativistic interactions. This provides a consistent interpretation of the changes in the symmetry and the number of physical characteristics of the crystal in the framework of the Landau theory within the temperature range 273 < T < 650 K.