A Comparative Study of Spin Magnetic Moment, Spin Polarization and Curie Temperature of Heusler type Compounds (A_2-X-YZ_y)Mnz (A = Ni, Pd, Pt And Z = Sb, Sn)

Abstract

The Heusler type compounds (A_2-x-yZ_y)MnZ (A = Ni, Pd, Pt; Z = Sb, Sn; x = 1, 0; and y = 0, antisite defects of Z atoms) are investigated to understand the induced magnetic properties. The structural phases C1_b type half Heusler (x = 1, y = 0) compounds AMnZ and the corresponding L2₁ type full Heusler (x = y = 0) compounds A₂MnZ and some disordered compounds (A_1-yZ_y)MnZ and (A_2-yZ_y)MnZ (y = 0.01, 0.05) were calculated using the Korringa-Kohn-Rostoker Green’s function method. The antisite doping of 1% (5%) Sb retained (suppressed) the half metallicity at (Ni_1-ySb_y)MnSb, whereas the other compounds were found to be gapless in both spin directions. The density of states at the Fermi level exhibits the explicit spin polarization in the compounds. The net magnetic moments of the compounds are closer in their values, wherein the manganese atom is responsible for the major contribution to the magnetic moments, which is much larger than the partial moment of the other constituents. The Curie temperature (T_C) of the ordered ferromagnetic compounds was estimated using the mean-field approximation. The TC higher than the room temperature was found for the ordered compounds, except for the cases of Pt₂MnSb and Pt₂MnSn. No literature value of T_C has been reported yet for these two compounds. Calculated spin moments and TC agree well with the experimental results, where available.

J. Bangladesh Acad. Sci. 45(2); 217-229: December 2021