Features of the Crystal Structure and Magnetic Characteristics of the Solid Solutions Ni_1–xM_xMnSb (M = Fe, Co) Systems

The results of studying the effect on the crystal structure and magnetic properties of compounds based on NiMnSb when Ni cations are replaced by Fe and Co cations are presented. The solid solution Ni_1–xM_xMnSb (M = Fe, Co) systems were synthesized by the method of solid-phase reactions. With the help of X-ray diffraction analysis, the presence of a concentration structural transition was established. Using the ponderomotive method, it was found that the temperatures of the “magnetic order – magnetic disorder” phase transformation decrease as nickel is replaced by iron and cobalt. The field dependences of the specific magnetization demonstrate the typical behavior of a magnetically soft ferromagnet. The results of an experiment on the study of the crystal and magnetic structure of solid solutions of the Ni_0.90M_0.10MnSb (M = Fe, Co) systems using thermal neutron diffraction in the temperature range of ~(3–300) K are presented. It is found that the studied compositions exhibit ferromagnetic ordering along the c axis. On the spectra of Ni_0.90Co_0.10MnSb solid solutions in the region of 2Θ  = 28.6° the appearance of a reflection indicating the formation of antiferromagnetic ordering is observed. Within the framework of the density functional theory, an ab initio calculation of the magnetic moments for Ni_1-xM_xMnSb (M = Fe, Co; x = 0; 0.125; 0.250) was carried out. The results of theoretical calculations predict the existence of magnetic moments for Fe and Co ions, and they are antiferromagnetically coupled to the spins of Mn and Ni ions.

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