Mössbauer Study of a Random Mixture with Orthogonal Spin Anisotropies: Fe_1−xCo_xCl₂·2H₂O

Abstract

Mössbauer spectroscopy has been applied to a random mixture with orthogonal spin anisotropies, Fe_1−xCo_xCl₂·2H₂O. The direction of an “individual Fe spin” of Co(Fe)-rich samples determined from the Mössbauer spectra was tilted even in the antiferromagnetic (AF) phase as well as in the mixed ordering phase. This means that, in the Co(Fe)-rich AF phase, although the spin component parallel to the easy axis of FeCl₂·2H₂O (CoCl₂·2H₂O) has no long-range order according to the neutron scattering measurement, the component exists on each lattice site statically at least in the time scale of ⁵⁷Fe Mössbauer spectroscopy (∼10⁻⁸ s).
The direction of an “individual Fe spin” has been shown to be strongly affected by the local environment around the Fe spin.