The magnetization behaviour at orientation transitions: TmFeO₃, ErFeO₃

The magnetization of the TmFeO3 single-crystal is studied in a Γ4-Γ24-Γ2 spin-rotation temperature interval. The magnetic moment projections on the a and c crystallographic axes are measured by a SQUID magnetometer and used to calculate the absolute value of magnetization |M|(T) and its rotation angle θ(T). The results are compared with the data obtained on ErFeO3 samples. While the |M|(T) θ(T) curves for the two orthoferrites are quite different, both are well described by the modified mean field theory, suggested earlier by the authors. The theory does not involve the fitting parameters and its experimental verification in the other material demonstrates the generality of the proposed description of Γ4-Γ24- Γ2 orientation phase transitions in orthoferrites.