ИСТИНА

The Dy2Fe10Al7 compound was prepared by induction melting method. The crystal structure and phase composition of the powder samples were determined by X-ray diffraction analysis. The diffraction pattern indicates that the Dy2Fe10Al7 compound has rhombohedral Th2Zn17-type structure (with R3m space group). The field dependencies of magnetization σ in the 4,2-300K range in magnetic fields up to 100 kOe were investigated. Noteworthy the curves σ(H) are not saturated in high fields up to 100kOe both at T<Tk and at T>Tk. The temperature dependencies of MCE were investigated in magnetic fields up to 70kOe. The change in the MCE sign from positive to negative in the region of compensation temperature is observed. The maximum of MCE below Tk shifts to lower temperatures with increasing magnetic field. In the region of Curie temperature Tc ~ 235К the MCE maximum is also observed. The molecular field theory for magnetisation and MCE description is used. The estimations of the effective exchange field value near Tk are made on the basis of this theory using the experimental data. The obtained value is in good agreement with that reported earlier for Dy2Fe10Al7 compound. The obtained experimental results and theoretical estimations show that the temperature and field dependencies of the MCE in the ferrimagnetic Dy2Fe10Al7 differ from those in ferromagnetic materials. MCE inversion at Tk is specified by magnetic ordering of rare earth sublattice under applied magnetic field at T<Tk and disordering under applied magnetic field at T>Tk.